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Carver P4 Blown Air Heater - Advice Needed on Removal


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I recently bought my first campervan (Autosleeper Symbol / Peugeot 2.0L petrol) and am in the process of doing one or two jobs before I put it on the road in April.


The heater blows cold air but not hot. The green light on the control panel glows initially but after a while it changes to 2 red flashes. The fan just continues to blow cold air.


I looked at the troubleshooting guide that came with the van and it suggests 'Blocked flue or intake' or 'Combustion motor or fan proving failure'


The van has a Carver Cascade water heater which seems to work fine (I could see exhaust gases from the flue when I looked out the window)


My problem is how to remove the P4 unit for inspection and testing. It's housed in an extremely solid and well built compartment under the long seat/bed. I can see the inlet and outlets both of which seem clear from obstruction.


I am guessing that the unit can be removed from the outside but I thought I would ask first before attempting to dismantle it as it looks like it the 2 units share a common flue.


I know that it's a gas appliance and I am likely to have to sent it away (somewhere?) for repair.


Many thanks,


Chris (?)

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Welcome to the Out&AboutLive forums, Chris.


The Carver P4 was a pure ‘blown air’ heater (images attached below). It will be completely independent of your Symbol’s Carver Cascade water heater and will not share a common flue.


As may be apparent from the upper image, the P4’s air input and exhaust (silver tubes coming out of heater’s lower side) would normally be led through a motorhome’s floor. Conversely, the flue for a Carver Cascade would emerge from a motorhome’s side (or rear) bodywork.


(I suspect that, when you say "I can see the inlet and outlets both of which seem clear from obstruction” the things you can see are the P4’s two air outlets.)


It’s near certain that removal of your Symbol's P4 heater will NOT be from outside the motorhome. So, as it’s buried in a box under the seat, that box (and possibly the seat unit too) will need to be dismantled to gain access.


This 2016 forum thread




discussed the P4 and the final posting (22 April 2016 6:37 PM) includes links to two possible repairers.


I suggest you also register on the Auto-Sleeper Motorhome Owners Forum (ASOF)




as that’s where the knowledge/expertise relating to older Auto-Sleepers motorhomes now lies.



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I had a P4 in my 97 Symphony (forerunner of the Symbol) and I had to remove it when it packed in. Luckily I picked a good one up on eBay. The P4 is definitely removed from inside. A bit of dismantling of the surrounding area is required but it's not too hard, just not a lot of room to manoeuvre. You have to work inside and underneath together in order to extract the two flue pipes.

There is a dealer on eBay who reconditions them , just search Carver P4 and it's usually the first item to appear. Someone with a 2000 Symphony posted yesterday on FB group asking if P4 could be replaced with a different heater. If that was you, I posted the eBay link there but also suggested it could be replaced with a Propex.

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As I said in my posting above, two possible Carver P4 repairers were referred to in the 2016 forum thread I provided a link to. These are A & R Electronic Developments Ltd at Cannock (which is the firm that will show up via GOOGLE-search)




and Arc Systems




that’s a one-man band (Gary) and may not still be trading (using the mobile phone number is said to be the best way to make contact).


As Paul says, there are Propex and Whale blown-air heaters that could be fitted as a P4 replacement




and Truma offers the “VarioHeat” unit.



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Going back to your original posting, as your heater displays the ’two red flashes’ symptoms referred to in the trouble-shooting guide (copy attached below) the first thing to ensure is that the P4’s air intake and exhaust flue are free of any obstructions.


An obstruction sufficient to put the heater in fault-mode might be spiders’ webs in the air intake tube - not too surpisingly with elderly motorhomes where the heater might not have been serviced for years and the vehicle has been out of use for some time.


The photo of a P4 installation in my first posting above suggests that (in that instance) it should have been possible to detach the intake and exhaust ‘pipes’ without having to move the heater itself, but Auto-Sleepers’s installation may prevent this. Definitely check that the there are no obvious obstructions in the pipes underneath your motorhome. Received wisdom seems to be that the P4’s printed circuit board should be a prime suspect if a fault occurs.


These USA links may be of interest, with Part 2 showing the ‘guts’ of a Carver P4.










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  • 2 weeks later...

Hi Derek,


Thanks for all the info.


I ended up sending the unit off to A.R.Electronics for repair. The problem was down to a fault on a board so that the unit wasn't sensing airflow, so it never got to ignite.


Repaired and serviced and back working in the van now. Great!


One final question on this topic. When I removed the inlet and exhaust ducting from through the floor of the van I noticed that they had been sealed with a tough black rubber compound around the exit points. Any idea what product could be used to make it watertight again?


Regards ;-)

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I believe the Carver P4’s exhaust ducting is double-skinned to guard against the possibility of scorching when the flue is led through (say) a wooden floor, so it probably won’t be essential that a sealant be heat resistant. But if you need to buy sealant, it might as well be the heat-resistent stuff in this case.


(In the 199os a few UK-built motorhomes were fitted with the Atwood Confort 3 gas/230V combination air/water heater and this was often installed in the base of a wardrobe with the exhaust flue leading upwards and emerging from the motorhome’s roof. The snag was that the flue was poorly insulated and became hot enough to scorch clothes in the wardrobe. Owners of motorhomes having the Confort 3 soon learned that a wire mesh shield should be fitted to stop clothes from touching the flue.)

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