Isotherm basic 40 water heater problem - PRV?

[Plan_B]

My boat system has developed a pressure fault. The cold water pressure is really good even with 3 taps open, and so was the hot until recently. It now the hot just trickles out of the taps and the pump (newish) just pulses. When cold water is drawn the PRV (Pt. No. SDF 00005AA) which is fitted on in coming connection to the storage tank makes an intermittent squeaking noise and I'm wondering if there might be a fault with the PRV which is telling the pump that the hot water line is up to pressure when it is'nt.

The UK Isotemp agents no longer have a technical dept and my local dealers have no apparent technical knowledge. I could strip the part down to see if there is any corrosion/damage/internal restriction but as I am living on the boat for a few weeks I need to use the system all the time and a new part has to be ordered and will take a few days to arrive.

Done a search on the Forum but cannot find anything specific.

Grateful for any ideas or experience with a similar problem.

DD

 

[nigelmercier]

The PRV may have a knob you can rotate to open and close it. Try turning it a few times.

 

[pvb]

The function of the PRV is simply to prevent pressure in the tank getting too high - if it does, water will leak out to relieve the pressure. It can't affect the normal operation of the system.

I imagine you have a thermostatic mixer valve fitted, and I'd be tempted to check that first.

 

[Plan_B]

Thanks Nigel and Pvb.

There is no Thermostatic mixing valve, the mixing is carried out at the monobloc taps. The thermostat is on the immersion element. This PRV is non adjustable, it does have a little blue manual toggle lever which I have operated vigorously several times to clear any debris although there is no evidence of this.

DD

 

[nigelmercier]

Open the pressure valve and connect a mains pressure hose to the hot tap, turn both on. This will clear any debris or airlocks.

 

[pvb]

There is no Thermostatic mixing valve, the mixing is carried out at the monobloc taps.

In that case, it would seem to indicate some sort of blockage in pipework somewhere. You might start by taking the pipe off the hot water outlet of the calorifier (turn pressure pump off first!), then turn pump on and see whether water flows freely out of the calorifier. If it does, look for kinks, etc, in the hot water pipework. This method is a little more user-friendly than Nigel's suggestion!

It would be worth fitting a thermostatic mixer valve - most new calorifiers now have them - as it helps conserve hot water.

 

[PCUK]

In that case, it would seem to indicate some sort of blockage in pipework somewhere. You might start by taking the pipe off the hot water outlet of the calorifier (turn pressure pump off first!), then turn pump on and see whether water flows freely out of the calorifier. If it does, look for kinks, etc, in the hot water pipework. This method is a little more user-friendly than Nigel's suggestion!

It would be worth fitting a thermostatic mixer valve - most new calorifiers now have them - as it helps conserve hot water.

I would like to be associated with the previous members comments!