Truma Pressure Release Valve (1 Viewer)

[SpitzTM]

Hi, does anyone pls know how the pressure relief facility on a Truma 6e boiler system is meant to work?

We have a new Benimar and on two consecutive days we have heard the sound of pressure being released by the boiler followed by water leaking into the van as well as from underneath outside. On both occasions we had set the water temperature to hot/boost.

The van is back with the dealer for repair, but just wanted to understand if it is normal for the pressure release process to occur each time hot or boost is selected for the boiler water temp.

This is our first motorhome so have no experience with Truma heating systems.

Thanks

 

[mitzimad]

theres two valves that can dump water one is temperature operated and the other is presure operated it would be easier to advise if you could photograph the type of valve directly above where it was disharging under the van

 

[mitzimad]

this is the usual one for pressure relief

this is the newest version of the temperature one some older ones have a knob on top which drops to release
there is also an electrical type that will dump if you lose power

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[SpitzTM]

Thank you mitzimad. I have a few pictures taken when the incidents occurred, do they help pls?

The last picture shows the base of the seating cabinet which houses the boiler and from which water has appeared each time, soaking the carpet. Looking inside the cabinet it was not obvious where the water was coming from.

We definitely heard a ‘whoosh’ type sound followed by the pump starting up and then the water appearing inside and outside the van. I switched the water pump off at the Truma control panel to stop the flow of water.

 

[SpitzTM]

this is the usual one for pressure relief

this is the newest version of the temperature one some older ones have a knob on top which drops to release
there is also an electrical type that will dump if you lose power

The water first seemed to appear below this valve (but not clear if it was from the valve itself). I thought this valve should only function in the event of low temps tho?

 

[Lenny HB]

I think the one you are having a problem with is the T piece on the side at the top of the boiler it has a clear pipe connected to it that goes under the van.
It is there to release air when the boiler is filled, they often go faulty and then water runs out the clear pipe when the pump operates.
In your photo it has the red hot water take off pipe & the clear drain tube connected to it.

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[SpitzTM]

Thanks Lenny. There did not appear to be any water in the clear tube when the problem occurred. Rather it was coming out onto the floor close to the temp valve (under the blue pipe in the attached picture).

 

[Lenny HB]

That is just the frost protection valve, it should dump the boiler contents if the temperature drops to 3°c.
Maybe faulty or just a bad connection to and it only leaks when under pressure when the pump is running.

 

[kevenh]

this is the usual one for pressure relief

this is the newest version of the temperature one some older ones have a knob on top which drops to release
there is also an electrical type that will dump if you lose power

Isn't the top pic a manually operated water heater dump valve?

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[SpitzTM]

That is just the frost protection valve, it should dump the boiler contents if the temperature drops to 3°c.
Maybe faulty or just a bad connection to and it only leaks when under pressure when the pump is running.

Hmmm, I’m starting to wonder if that blue pipe into the temp valve is connected properly (as you are suggesting). Is the water in that pipe under increasing pressure as the boiler heats the water?

 

[Pablotti]

Our 2017 Benimar did the same… but not inside. My understanding is that the pressure of heating the water needed to be released. It would occasionally come out from under the van below the Truma unit when heating water.
I never saw the actual valve. I would guess that the pressure outlet pipe is not correctly fitted to the truma, or the unit itself is faulty.

 

[daveandsan]

Thanks Lenny. There did not appear to be any water in the clear tube when the problem occurred. Rather it was coming out onto the floor close to the temp valve (under the blue pipe in the attached picture).

My pressure relief valve operates regularly when the water is heating up from cold.
The water should exit under the Motorhome, you must haves pipe with a loose connection.

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[SpitzTM]

So, just tie up the loose end here, it turned out the problem was due to the pipe connected to the the PRV was passed through a hole drilled in the wrong place and had become ‘pinched’ thereby not allowing the pressure and associated water to pass outside the van. The dealer redrilled the hole and reconnected the pipe. We have since used the van on a very pleasant stay in the Forest of Dean and the problem has not reoccurred.

Thanks for all the helpful comments!

 

[mitzimad]

Isn't the top pic a manually operated water heater dump valve?

it can be used for that but its main purpose is as a pressure release valve its sprung loaded to open at a certain pressure when you lift the lever you can feel the resistance of the spring If your thermostat fails the water heater is a potential bomb this lets the excess pressure release to safety under the van