Calorifier problem

[Magic Potion]

Advice needed please.

Having just filled my water tank, I noticed a constant flow coming from a skin fitting linked to the calorifier. If I turn a tap on, it stops, when the tap is off it starts again.

Any ideas welcome.

[dor]

Your PRV valve is stuck open or is wrong pressure for your pump.

 

The PRV valve will be near the calorifier probably with a red knob on it. Rotate this a few times and it may clear the scale that is holding it open. It should be a 3 bar one - it may say it on it somewhere.

 

It has to be a higher pressure rating than the waterpump cutoff pressure. It is there to release excess pressure as the water expands on heating. Do you have a pressure vessel on your system? Like a big tin can attached to a pipe somewhere.

 

EDA: Does it only happen when the water is heating up - either by running the engine or using a heat source?

Edited August 7, 2014 by dor

[Magic Potion]

Sorry for late reply. It slows to a trickle when I switch the water pump off but when it's on it's like an extra tap. Water pump is a shurflo 3901. Its only just started doing it this week. There's an accumulator next to the water pump. Not noticed it when engine not running .... will have to check.

[Murflynn]

 

The PRV valve will be near the calorifier probably with a red knob on it.

or may be fixed to the calorifier, in the case of a vertical cal it is probably incorporated with the hot water outlet at the top of the tank.

[Paul G2]

Tale a look at this thread: http://www.canalworld.net/forums/index.php?showtopic=68133&hl=

 

It's about someone with a similar problem to yours and might give you some background knowledge and a few ideas about things to test.

[nicknorman]

So in summary it is either due to the pump cutout pressure being too high, or due to a fault in the pressure relief valve - a fault that might be lime scale build-up or something else. As said, rotating the red knob on the PRV might clear the scale, if not you will need to replace the PRV. But first check the pump pressure. Presuming the accumulator is adequately pressurised, the air pressure in the accumulator (measure with a tyre pressure gauge) is the same as the water pressure. It should be a max of around 2 bar (30 psi) for a typical system with a 3 bar calorifier / PRV, just after the pump cuts out.