Work in Progress (wip) How to retrofit an Auxiliary Parking Heater (FBH)

[Keith]

This is an example of a WIP How to in response in this case to one being marked as "needed" in the relevant How to section but it could just as easily be a brand new one. and once complete will be moved to the How to section.

Always try to start with a brief introduction to the How to, its aim, and by all means PM people who you know can contribute.

Post Project Drive the Auxiliary Heater aka the FBH became an option in the CDT
A member has posted previously that all the fuel lines and cabling are however still in place

This How to will describe the procedure to

A, Retrofit the Auxiliary Heater
B, Upgrade it or an existing Auxiliary heater to a full blown Parking heater

The thread could when complete contain separate posts re the actual heater retrofit and posts detailing implementation of individually remote control solutions e.g. one for the Timer one for the Telestart one for a third party remote etc etc.

So who has retrofitted one and wants to start the ball rolling - Lovel?

[Spôôk]

I have got the manuals for the FBH R75 installation. They are in German, but you are welcome to download themand put them in the TechieForum.

http://vifa-as.dk/Webasto-75.pdf

and installation of the remote:

http://vifa-as.dk/Webasto-remote.pdf

I am not the author of any of these documents, but they are in free circulation.

Spôôk

[pondweed]

keith -
I've proposed some last questions(on .org 75/ZT forum today.. "does your cdt take ages to warm up") to an old thread with some of your contributions on the "relay-route", rather than that proposed in the german translations which spook has outlined.
With those questions answered, I feel I could attempt a complete "fools guide" for "that" route, which is what a lot of us need - diodes scare me. If you/someone answers that, I'll complete my installation and (if my car doesnt explode) I'll write it up including costs and sources of bits for the uninitiated like me?!

[Keith]

Jon Diodes are not necessary a DPDT relay to me is a better approach
but the net result is the same there are in normal use two separately fused power leads feeding the ATC control panel which when used with the FBH need to be powered up the diodes or relay does this by connecting them to a
power source when FBH is in use but allowing them to remain independently powered in normal use

[pondweed]

keith - I was agreeing with you..!

but from review of posted material over last year there are gaps in whats been posted to enable the less technically minded to complete the job I feel... stuff you would take for granted as 'background knowledge'.

hence my request re someone answering the specific questions on the refreshed thread on .org, to fill these gaps... so it can all be packaged here.

[pondweed]

I attach all this here copied from the last bit of the .org strand, so gaps can be filled...bits underlined still needed for writeup.

"replying to this as was searching for ages to find the actual wiring requirements for keiths/original "relay" approach for getting timer/ATC/fbh functioning as full parking heater.. and this thread from a few months back has it all, so good to bring it backup to the top of the pile!

Questions still to be clarified for the less electronically-able i.e. me:

1. does pin 4 need to be fused in line before it gets to the DPDT relay, and with what ampage?

2. Still looking for the actual wire connections for the Timer to relay to fbh...keith, someone, help!

I've got timer's positive going via 1A fuse then to 12V live supply

Timer negative supply direct to bodywork earth

bogstandard £2.69 12V relay has 85, 86, 30, 87 and 87a poles

Timer (positive) output to which pole?

fbh pin 3 to which pole?

which poles elsewhere, earth,wherever?

the guy that sold me the relay was adamant I needed a 1A emf diode as back suppression for avoiding damage to digital timer.. is this viewed as necessary or unnecessary by the combined R75 intelligencia? (and if so which poles is it between)
Sorry - loads of questions to fill the gaps, but I think with all this covered even one of the chickens could do this (well, not Lettie - she's hopeless) and so I' m happy to raise my head above the parapet and press submit.....


(keiths original text below... although notice that in other postings in this thread mattL suggests using a simpler access to the car insides via a spare grommet in the passenger plenum area)


Quote:
Originally Posted by Keith Alexander
The Diodes are there simply to maintain segregation of the attached circuits as DC only flows one way through a Diode so the switched supply from the Relay gets to the ATC panel but does not flow back through to any fused circuits also connected to the Light Green/White and White/Orange wires

They also provide segregation between the actual two Light Green/White and White/Orange wires.

I have no problem with that it is a perfectly ok thing to do and in normal circumstances the volt drop of about 0.7 volts would be acceptable but at the time I didn't know how the ATC Blower operated and I thought these wires or one of them were control feeds to the blower motors themselves and as the motor uses a variable stepping function to control its speed the volt drop could have affected that at lower speeds

I have since realised that both the Light Green/White and White/Orange wires are simply just at +12V and are both derived from the battery via different capacity fuses so no harm using diodes of a decent rating, plus it means you get a clean transition which keeps the ATC panel powered up should you turn on the ignition as at that time if using a correctly wired MT350 it will turn off.

The reason I used a relay was to keep it simple and more inline with how it is factory wired if you have one relay already providing power to the Diodes you might as well use a similar relay to do the whole job without the need for any diodes. I can leave my FBH running with or without the ignition on If I choose by doing it this way, obviously the T80 turns the system of itself after its preset time which by default is 30 minutes

I used a DPDT Relay (Double Pole Double throw) the two ATC wires from the ATC side go to the two common terminals, the two ATC wires from the Fused side go to the two normally closed terminals and the power from an appropriately fused supply is provided to both the Normally open terminals net result, relay off (99% of the time) the ATC panel is effectively wired exactly as standard but when the FBH is activated the relay switches over and both the ATC cables are connected to +12V

The other difference in my install is that I use pin 4 of the FBH to operate this relay again as per standard wiring, I thought at the time that maybe the FBH would only power up the ATC once it had got the core water circulating around the engine up to temperature first but again this does not seem to be the case as soon as you gnd pin 3 pin then pin 4 switches the relay

I looked for all sorts of ways to get a cable through, I will have a look for the route you chose but the attached pic gives a good idea of where I put mine. The cable is tied in to the existing loom, for orientation the bulkhead to the passenger footwell is on the right note the little Grommet could also be used for access. Also note I have fitted a spacing clip at top left as whilst under there I noticed the standard loom is very close to the exposed metal edge there was a fair bit of chaffing so the clip spaces the cable away nicely, don’t want any fires etc!

[pondweed]

a pulling together of several strands - for comments/additions and I will amend and update. Particularly interested in people's thoughts on the need for suppression and isolation diodes in the various possible places. Some do, some dont...

[pondweed]

this got removed somehow?

[Keith]

Cheers Jon

[GreyGhost]

Thanks for reposting the file. We lost loads of attachments a few weeks ago when the system crashed.

[black olive]

Is there still a requirement for a how to to retrofit the heater ?

If so I will put something together as I have a few pictures etc.

[CDTi]

Is there still a requirement for a how to to retrofit the heater ?

If so I will put something together as I have a few pictures etc.I'm looking into this at the moment - if I can get my hands on a working FBH :lol:.

Gary (Lovel) has already given me some great info and is very kindly sending me on some DVD stuff. But knowledge is no weight so it would be great f you could add whatever you have. Maybe between us all we can do an A to Z of the complete retro-fit.

[tapped]

Yep,

would love to know myself. Especially the relevant part numbers. I can then get them priced up and decide if I should buy one!

[black olive]

Right- Ill get on with it.

Tapped- I did have a print out from the dealer that gave all the part numbers, if Ive still got it I will include them, however tht was a very expensive route to go down ( for example £130 dealer rather than £30 ebay for the fuel pump)

[black olive]

HERE WE GO.

First of all Im not going into the detail of how to fit a remote timer or telestart as I didnt get that far, I cheated and used a toggle switch.

Also, the usual disclaimers re high temperatures/fuel etc. apply- If you dont know or are not confident in what you are doing, leave it to someone qualified ( these heaters are basically diesel powered central heating boilers !!)

First of all, here is a link to all the Webasto technical information, service manuals etc. I found this extremely useful.

http://www.techwebasto.com/thermosystems_automotive.htm

Its well worth reading the technical manaul to understand how the unit works and is put together

Below is a compendium of information gleaned from a very helpful Webasto technician who was involved with the development of the MGR installation

The heater units supplied to MGR differ to those available off the shelf as part of a kit or for a non rover application, in the following way.

Different pin configuration on the 6 pin connector
Coolant temps for switch over from full load to part load/idle
Different software install ( the intnet was to enable diagnostics via T4, but this was never implemented).

1) when checking for a duff control unit PCB, measuring the voltage at the fuel pump outlet with a DVM or similar is a bit fruitless, as in certain run conditions this can appear to be sat at a high voltage level, whereas a DC coupled oscilloscope would show that the line is actually pulsing ( the width of the negative pulses controls the amount of fuel pumped), or not if your control unit is damaged, or a lockout condition exists.

The heaters are (obviously) designed to fail safe, and lock out if all the conditions for their safe running are not met, the only sure fire way to diagnose any lock out conditions due to other infleunces on the system, or faults with the heater itself is to use the webasto diagnostic tool ( webasto diagnostics were never implemented in T4), available at any webasto dealer ( or I believe can be obtained from ebay).this will interrogate the controller IC for any logged faults or lockouts.

Keith has had some success with the webasto diagnostic software, see this thread

http://www.the75andztclub.co.uk/forum/showthread.php?t=12192&highlight=webasto

2) Early cars were released with fuel line joiners which reduced the effecive inner diameter of the fuel lines at the joint points to 0.8mm ID, this led to problems due to lack of fuel being supplied to the burner, causing lock out due to lack of fuel.Worth checking your fuel line runs, particularly as over the years these joiners may have become blocked with small particles of crud.

3) a batch of vehicles were released with potentially duff temperature sensors, so the heaters will never kick in unless commanded by telestart or similar remote devices ( ie will not run when engine is running and outside temperature less than 5 degrees)

4) Not all vehicles left the factory with the fuel lines to the FBH correctly primed- so the heaters on these vehicles will never have worked from day 1 . The solenoid pumps have to be gravity fed and are not self priming.

5) finally and most worringly, the units were carried over from a BMW deign, and had an inherent fault in that if the units are disconnected, the 2 way connector has to be inserted before the 6 way connector otherwise a chip in the control unit will blow. Webasto were not allowed to design this fault out for MG rover (cost) , so a number of units particularly those obtained from scrappers and retrofitted may be damaged in this manner.

I did ask on the availability of a circuit diagram. the response was that all the pertinent IP rights had been passed to MG Rover, so this information was no longer available via webasto. ( or obviously MGR)


NOW ONTO THE RETROFIT ITSELF

SOURCING A HEATER

Various sources exist for these items.
The first is Ebay- new items pop up occasionally, usually commanding a high price. Also foreign sellers have these on offer, the problem with these units is that they are not the correct MG/Rover units, and are generally faulty- even though the listing doesnt implicitly state this ( personally I would give these a wide berth). New kits for installation on boats are often listed- but at boat type prices ( I wonder if anyone actually buys these). The way I obtained my heater is to constantly scan Ebay for rover 75's being broken for spares, but you have to be on the ball- these seem to be one of the first items to be removed !!

Obviously you are buying a second hand unit, and unless it can be seen working you are taking a gamble- but if you can haggle with the scrapper, prices are reasonable, and you can ask for them to include the air intake silencer and exhaust ( also ask for the connectors as you may need some spare connector pins)

The other option is to buy new via X part

PART NUMBERS ARE LISTED BELOW.

a couple of pictures of my heater are shown below

the first showing the heater, exhaust pipe, and intake silencer

http://i128.photobucket.com/albums/p176/steve3452/PICT1748.jpg


the second giving a close up of the heater body

http://i128.photobucket.com/albums/p176/steve3452/PICT1752.jpg

REFURBISHING A SECOND HAND HEATER

I stripped the unit down, removing the air filter, water pump and connection pipe, combustion air fan cover, and control unit cover/PCB.

I removed and cleaned the air filter foam ( it can be pulled out from the housing with long nose pliers) , using washing up liquid solution, and allowing it to air dry , the outer housing was cleaned up with washing up liquid, and dried.

the alloy casing was given a good clean and repainted with silver spray paint.


the combustion fan was checked by applying 12 volts to its connector, this gave a healthy supply of air to the unit. a couple of hoses were attached to the water pump, and this was tested in a bucket of water ( note it is not self priming)


The glow plug was checked by connecting it to 12 volts, as it current limited my 2 amp power supply I assumed it was ok, the other check to do is its cold resistance (between 0.324 and 0.36 ohms at 25 degrees celsius, maximum test current 5mA))

I did not split the unit to decoke the burner, but some forum members have done this ( I cant find the thread) using caustic soda. As the burner is available separately you may consider treating this as a consumable item and fitting a new one. If you are not technically minded and have more in your wallet than moths it may be worthwhile buying a new heater assembly via X part- that way you know it will work and will have a guarantee ( although this may only be valid if dealer fitted )

see thread below for burner details

http://www.the75andztclub.co.uk/forum/showthread.php?t=10204&highlight=webasto


OTHER PARTS REQUIRED

Fuel pump. This is a combined solenoid pump, and shut off valve. Available via X part, or from ebay . A marine dealer in Jersey ( SARKBLUE) is very helpful, and can supply fuel pumps, timers, exhaust and inlet silencers all new and at reasonable prices.

Inlet silencer

As can be seen from the pictures the air intake silencer designed by MGR is a very neat unit. the alternative is a piece of flexipipe and universal silencer ( also functions as an air filter )

Exhaust

the MGR exhaust is a piece of thick walled stainless pipe. OEM fit does not have a silencer, however one can be bought quite reasonably ( was supplied as part of the rover 75 "comfort kit" which consisted of a timer, wiring loom, and exhaust silencer- I dont know if this kit is available.

Alternatively a silencer and stainless flexipipe can be obtained from ebay quite cheaply.

I ran my unit without silencer and didnt find it excessively loud

FITTING THE HEATER TO THE CAR

Before attempting to fit the heater, you will find it advanageous to remove the engine deadening cover, and the large bore pipe between the EGR valve, and the alloy housing containing sensor ( MAP SENSOR ?). thiswill give you more clearance in front of the battery box. I also removed and cleaned the EGR valve whilst I had its pipe off.

the heater is fitted to a bracket which will be fitted to the front of the battery box, using 3 m6 screws, I used stainless cap screws. Before fitting the heater, the exhaust will need to be sorted out, and fitted in place
If using an aftermarket exhaust you will have to use your ingenuity as to the layout- the outlet needs to point downwards under the car.



PLUMBING IN THE COOLANT PIPES

there is a long heater pipe in the engine bay that is clamped to the FBH bracket. on this pipe is a line marked " cut here for FBH".

I found there is no need to start draining the coolant system

I clamped the coolant pipe a few inches either side of the line before cutting, with a couple of G clamps and some pieces of thin ply, coolant loss was less than 1/2 a litre.

after fitting the cut ends to the FBH with jubilee clips, running the engine for a few minutes with the radiator cap off will bleed the system, there is a bleed screw moulded into the pip which should be unscrewed until coolant leaks out.

THE HEATER FITTED

http://i128.photobucket.com/albums/p176/steve3452/fitted.jpg

THE MAKESHIFT CLAMPS

http://i128.photobucket.com/albums/p176/steve3452/clamp1.jpg

http://i128.photobucket.com/albums/p176/steve3452/clamp2.jpg
THE FUEL FEED PIPE

The blanked off black pipe on the right of the grey pipe is the fuel feed pipe

http://i128.photobucket.com/albums/p176/steve3452/dieselpipe.jpg



FITTING THE FUEL PUMP

fitting the pump was a doddle, under the car in front of the offside rear wheel there is a bracket with two captive nuts on it and one of these was used to locate the rubber mounting that came with the pump. The manual recommends tilting the pump upwards slightly so air bubbles flow up the line.

before fitting this you will have to remove the rear seat squab, under this there is a fuell tank blanking plate on the offside, removing this will expose the top of the in tank fuel pump, and you will find a stowed loom with a 2 pin connector. push this down in front of the tank unitl it pops out where the bracket is located.

the line from the tank to the engine bay is blanked off by a plastic part, remove this from the bracket, and unplug the pie ends from it ( self explanatory when you see it in situ)

I pre-bled the line from the tank by attaching a large syringe to the line and sucking until the syringe filled with diesel, and then pushed this line onto the pump.
I then pumped the syringe full of diesel up the pump output line, to prebleed this line with diesel also, plugged this pipe into the output end of the pump,and
attached the other blanked off end of the line ( in the engine bay) to the FBH. the 2 pin connector was then connected to the fuel pump ( the connector should be blanked off, this blanking plug will have to be removed)

http://i128.photobucket.com/albums/p176/steve3452/PICT1783.jpg

ELECTRICALS

You will have to fit a 15 amp fuse to F8 in the engine fusebox, this will provide the feed to the 2 pin power connector ( this and the 6 pin connector will be stowed in a plastic bag under the battery box- they are fitted with blanks that have to be removed).

the connectors then need to be fitted to the FBH ( 2 pin connector first)

TESTING

to test the heater pin 3 needs to be earthed . If you have a spare connector, pins can be removed by carefully unclipping and taking out the coloured insert with a jewellers screwdriver, the pin can then be pulled out after releasing the barb with the jewellers screwdriver ( harder to explain- self explanatory with the connector in front of you- I should have taken pictures !!)

after earthing pinn 3, the combustion fan will start up, and then ramp down, at the rear of the car, the fuel pump will start to tick. Shortly after the heater should fire up, and teh air fan will ramp up again, the heater willl start to sound like a small jet engine, and the exhaust and coolant pipes will warm up. after a while the heater will ramp down to idle mode.

You will also need to test that the external temperature sensor fires the heater up. I never got round to this, but the sensor is located at the bottom of the radiator and if this is cooled with electrical freezer spray whilst teh engine is running, the heater should operate.

PARKING HEATER MODE.

A number of ways exist to convert the heater to a parking heater. I used the simple method of a small toggle switch which I mounted in the nearside plenum cover plastic grille so I could get at it with the bonnet closed. I have to take the dog for a walk before work so on a cold morning switched the heater on on the way past.

you can also use a timer or telestart remote control. My preferred option would be a timer as no manual intervention is required, and the timer is a deal cheaper than a telestart.

wiring info for either option is available via this thread, perhaps someone who has done this mod can append the information here





PART NUMBERS

my very helpful X part dealer ( Dutton Forshaw Blackpool) helfully provided me with a printout from EPC which gives an exploded parts breakdown of all the parts required to do an FBH fit,

the file path is ROVER 75 AND MG ZT / COOLING HEATING AND AIR CONDITIONING / HEATING AND VENTILATION / HEATER ASSEMBLY FUEL BURNING HEATER.

If you want to go down the X Part sourcing route I suggest you try and obtain this printout- it goes down to tie wrap, screw, and nut level.

As this info is readilly available I will just list the major parts

JEC 102161
JEC 104390
JEC104391 HEATER ASSEMBLY FUEL BURNING- This is the unit itself, Im guessing the different parts are for different chassis numbers, they may be interchangeable

JEX 100090 PUMP ASSEMBLY FUEL BURNING HEATER UNDERFLOOR TO BODY - This is all the parts required to mount the pump, including the pump. note that mounting the pump supplied from sarkblue is a LOT simpler and does the same job for less cost.

JEY 100042 SILENCER FUEL BURNING HEATER AIR INTAKE

JEZ 000170 PIPE EXHAUST FUEL BURNING HEATER

As already stated, numerous pipe clips, jubilee clips etc are listed, most are probably onthe car anyway as part of the FBH provision.


Well I think thats it- apologies if it seems long winded but I wanted to include as much info as possible.

please feel free to add any other pertinent information

[CDTi]

Excellent work :bowdown:.

With this "how to" and the HUGE amount of information that Gary (Lovel) has given me, then this job is looking real easy :).

I had a second-hand FBH sent to Keith for testing. He should have it by now and hopes to get it tested at the weekend.

[black olive]

FINISHED- if anyone has queries add them to this thread and I will try to answer them
also if anyone can proof read the text it would be useful

[tapped]

Top man Steve

I can buy Xpart stuff reasonaby hence the qu about part no's so this will be very helpful.

I've got till next winter to get around to doing it now :D

[CDTi]

That really is excellent, Steve.

I now have a fully working second-hand FBH thanks to Keith :bowdown:.

He had to do some work on the unit I sent to him, but it is now fully operational.

Total cost including all postage etc was a little over £200 i.e. cost of second hand unit, repairs etc. I think thats pretty OK.

I should hopefully have it here in Ireland sometime next week.

Thanks again Keith :).

[GreyGhost]

Thanks Black Olive, I have copied your post into the How To forum and locked it in. I'll have a second read through later to check spelling etc. but looks good to me on first reading.
http://www.the75andztclub.co.uk/forum/showthread.php?t=17238

[CDTi]

One question - is the ambient temperature sensor already in place?


Oh - another question :). Should some kind of rubber mounts be used to mount the heater or just ordinary bolts?

[black olive]

I believe the sensor is in place, but didnt confirm it on moodyblue.

no the heater bolts directly to the mounting bracket

[CDTi]

Yep, looks like I have the sensor :)

Gary (Lovel) sent me a drawing today that shows what it looks like.

When I checked my car I found this:

http://www.the75andztclub.co.uk/forum/imagehosting/3347d44fbf644c0.jpg

[black olive]

thats the one- thinking about it moodyblue did have one, but never got round to checking whether it kicked the heater in.
with the engine running, if it is given a good blast with electrical freezer spary the heater should kick in

[Jules]

There's another outside air temp sensor mounted just above that one in CDTi's pic. (just hidden by the bottom of number plate)

I thought the round sensor shown was to do with the power steering cooling pipes next to it.

[CDTi]

IIRC this sensor was mounted onto the rad frame. There were 2 wires exiting from the back.

I'll have a look again tomorrow.

[CDTi]

Gary (Lovel) sent me a lot of information on this. I'm sure he won't mind me saying he keeps extremely detailed records :bowdown:. I wish I did the same.

One of the very helpful things he sent was a circuit diagram of the entire parking heater configuration. Although its for a Freelander, I think the only differences are with the 6 pin plug on top of the FBH. Gary may be able to clarify.

As a few members on here are currently looking at doing this, here is the diagram:

http://www.the75andztclub.co.uk/forum/imagehosting/3347dd817f109ad.jpg

[Lovel]

Apologies if I am mixing up vehicle models here, I feel the info is relevant and may help contribute some info to someone, so feel free to remove mods.

These attachments may be quite handy reference for anyone installing the parking heater and FBH. They are for the Freelander, but I'm sure if you follow the Rover 75 wiring diagram you will be able to adapt the wiring to suit.

The install was carried out on a 2001 Freelander with manual heater controls. This installation with modification to suit car wiring may be applicable to Rover 75 Classic SE models with manual heater controls too.

[tony_fry]

Does any one know the diameter of the exhaust pipe as I want to fit a silencer but there are two different sizes on eBay a 22mm and a 24mm or if some one that has one fitting possibly a part number from it.

Thanks
Tony

[CDTi]

I have mine fitted, Tony, so I have no idea of the diameter. I may be able to measure it from underneath - I'll give it a try today or tomorrow.

From what I can tell from the EPC, the exhaust part number is JEZ100125. The complete exhaust (includes the muffler, etc) is JEZ000170.

[ianw]

hi there the answer to your question on the diameter of the fbh exhaust pipe are 26mm external and 23mm internaly

[Jakg]

What size jubilee did you use for the coolant pipes?

[Greeners]

What size jubilee did you use for the coolant pipes?

Just use the ones you take off when you split the pipe...

[Jakg]

Ah does it already have them on there?

[Greeners]

Ah does it already have them on there?

There should be a short plastic pipe that joins the 2 pipes together......

[autopia]

Great thread, many thanks to all who posted on this one and all the other FBH threads, really useful info for retro fitting an FBH.

I bought a 66232C unit off ebay last week and got it running today, thought I'd add some (maybe) useful pointers to the excellent threads.

Priming the pump and fuel line required a little persistence and ingenuity, the pump needs to be connected the correct way, i.e. with the electrical connector on the inboard side, the tank feed pipe is the one on the outboard side, the FBH feed pipe (one that goes to the engine bay) is on the inboard side along with the electrical connector.

I primed it by using a vacuum tool (normally used for bleeding brakes) then manually pulsing the solenoid pump with a 12v supply, took me about 2-3 mins to get fuel to the front.

Visiting a scrapyard on Saturday for a turbo intercooler resulted in increasing my FBH count to two, this time a 98570B, so I took the opportunity to test both units.

Although the pin 3 to earth method works on the 98570B, the 12v to pin 1 method works on both units so I cut back a little of the insulation on the wire to pin 1 using a scalpel and was able to start each unit by touching the bare wire with a 12v supply, however I found that just clipping the wire on didn't always start it up, I needed to pulse the supply then clip the 12v onto the bare wire, it seemed to be the 12v dropping that triggered the unit, clipping the 12v onto the pin 1 wire just maintained the FBH running - when I rig up a remote unit, I'll need to figure out how to send the pulse then maintain 12v on pin 1.

My under bumper sensor stayed open circuit, no matter how much freezer I sprayed on it, I'd picked up a spare sensor with the FBH on Saturday and buzz testing it confirmed it worked when chilled, swapping it was a 2 minute task and it tested OK with the engine running and spraying the last of my freezer spray on it.

In summary, both units work well with hot water circulating in 2-3 minutes, and after 10 mins, I got hot air through the vents which should help in the winter months, but the noise is great, sounds like gas turbine firing up!!

Next steps are to rig up a switch timer, probably the maplin one although I need to modify it to give me 30mins, then add a remote switch to start the timer, finally, I'll look at using the 66232C unit to switch on heating control - but can anyone confirm that it should interface with the dual zone climate controller unit???

thanks again