TRUMA COMBI BOILER 6 E (1 Viewer)

[Alymar]

Hi everyone, hope you are all well.
I need some help with my combi boiler. I have a two year old Rollerteam motorhome. When I put the water heater on regardless of whether I choose Eco,Hot or Boost or Electric or Gas after approx 13 to 20 minutes the Truma relief valve spits out cold water, which makes the pump repressurize the system which then spits out more water , and this cycle just keeps going until I turn the pump off.
Has anybody had this problem and if so what did you do to fix it. Thankyou in advance.

 

[PJGWiltshire]

Has the temperature symbol stopped flashing showing that it has reached the required temp. If it has reached that temp and a while after doing so the PRV then starts kicking in, consider having the thermostat looked at. If this is faulty the water will continue to overheat thus increasing the pressure

 

[Landy Andy]

Sounds like the relief valve pressure, and the system pressure is too close, possibly because of one of them getting lazy. Our relief valve goes once when the boiler is up to temp due to the water expansion. But only the once.

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[Alymar]

Hi thanks for help. When the problem happens the symbol is still flashing so water is not at temperature.

 

[Landy Andy]

If you stop the cycle, is it then ok?
So if you remove the pressure from the water system, then run boiler up to temp, once up to temp turn pump on is it then ok?

 

[PJGWiltshire]

I had a couple of PRV burst back in 2019. Decide to change the small valve(about £10 spare part) as Carthago service outlined to me that the small plastic preventer may have weakened thus is activated under pressure. Did this and have never had an issue since

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[Alymar]

Hi thanks for you reply. If I turn the pump off It stops the pressure relief valve from constantly opening, If I then turn pump back on It starts cycling again. If I leave pump off until water is at temperature then turn pump back on there was no cycling, I left it like this for 1 hour and there was no cycling. Thank you

 

[PJGWiltshire]

I wood change the PRV. If you are still in warranty get this done by the dealer

 

[Alymar]

Trouble is this is a new prv. I heated water up today with the pump turned of. The prv expelled water after 25 minutes and 45 minutes, so this would say the boiler created enough pressure to open prv without the pump pressure.

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[PJGWiltshire]

If you are able measure the temperature of the water that may point you towards the thermostat. If I recall the hand book gives the temperature of the water at the settings see if the water temp over heats

 

[PJGWiltshire]

Have you changed your water pump? The water pressure should not exceed 2.8bar

 

[PJGWiltshire]

Trouble is this is a new prv. I heated water up today with the pump turned of. The prv expelled water after 25 minutes and 45 minutes, so this would say the boiler created enough pressure to open prv without the pump pressure.

If the pump has fed the system and turned itself off. Then the system is now under the full pressure set by your pump. By turning off your pump now the system is still under that pressure. Try priming the system with the pump. once it turns itself off then switch the pump off. Then open a cold and hot tap just to let the water quickly flow and thus reduce the water pressure of the sealed system. Then turn on your boiler from cold and see if it then activates the PRV not under pump pressure.

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[Alymar]

The water pump has been changed like for like. It is a fiamma aqua 8 and is rated at 1.5 bar with no adjustment.