Calorifier (again)

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peter2407

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My calorifier is weeping (as am I). I thought it was the PRV. Talking to the supplier today to source a replacement, he thought it might actually be doing its job as that the water pump was playing up. I haven't changed it at all, so I was quite dismissive of the pump being the issue but when I was on the boat over the weekend, I had to replace a broken in line non return valve on the feed in. I looked like it had decayed, but I am wondering if the breakage is as a result of over pressure. Thoughts?
 
By weeping, I mean that there is a very slow leak coming from, I think, the PRV valve. I was going to go straight to replacement, but the supplier recommended looking at the water pump, as the 'weeping' may not be a fault with the valve, but evidence that it is actually doing its job re releasing pressure build that may be caused by the water pump constantly pumping. I was dismissive of that but then started to join the dots re the broken NRV on the input from the FW tank to the Calorifier tank. Apologies for not being clearer first time round.
 
Seems to be some fundamental misunderstanding here. The pump delivers a pressure that is controlled by a pressure switch. The delivery pressure should be less than the value of the PRV in the calorifier. If the delivery pressure is greater than the PRV rating, the latter will leak. This can be caused by a fault in the switch, or in some pumps there is an adjustment. If the pump is operating frequently it is an indication that there is a leak somewhere. The NRV failure has absolutely nothing to do with your problem, most systems don't have one.

Firstly, check the PRV, make sure the valve is seating on metal, not on calcified salts, the most common cause of leakage. If it is working OK, look at the pressure switch. If the pump continues to operate constantly, look for leaks first, then next look for debris in its valves.
 
Thanks Vyv. The reason that I initially doubted the pump question was because I dont leave it on when away from the boat, so it couldnt be constantly pumping into the calorifier tank, inducing the PRV to activate and "weep". I will take the PRV off tomorrow and give it a check and rinse.
 
peter2407 said:
Thanks Vyv. The reason that I initially doubted the pump question was because I dont leave it on when away from the boat, so it couldnt be constantly pumping into the calorifier tank, inducing the PRV to activate and "weep". I will take the PRV off tomorrow and give it a check and rinse.
Click to expand...

If the PRV is weeping all the time, even when the pump is switched off then it definitely needs a good looking at, possibly even replacing.
 
Very recently my water system was showing similar symptoms to those of the OP's. The first sign was that of the water pump cycling every couple of hours. A cursory examination of the calorifier showed a slow but persistent drip from the PRV. Upon checking up on the price of a replacement PRV I decided that I'd better first be absolutely sure that I needed one. A more thorough examination revealed that actually the tank had sprung a leak. I found a very small pinhole in the weld attaching the cold inlet pipe to the tank. Leakage water was trickling along the inlet pipe until it reached the PRV and gravity taking it over the PRV. The cause of the leak was so small that I could only detect it by pressurising the tank using a bicycle pump, applying a soapy water solution around the weld line and looking for bubbles.
 
Thanks. As part of my post VicS tests I will put the drain pipe from the PRV into a container so if it is the PRV the water should collect there, I will ensure that is also underneath the PRV. If not then it is soapy water time ..
 
A few weeks ago my FW pump started playing up. Cycling every few hours and on two occasions the PRV on the calorifier went off with a loud clacking sound.

I replaced the pump as the micro switch had failed and was not reliably turning the pump off. The new pump is much quieter and no more alarming noises from the PRV.
 
Sophie19 said:
A few weeks ago my FW pump started playing up. Cycling every few hours and on two occasions the PRV on the calorifier went off with a loud clacking sound.

I replaced the pump as the micro switch had failed and was not reliably turning the pump off. The new pump is much quieter and no more alarming noises from the PRV.
Click to expand...

Generally the pressure sensor complete with or even the micro switch on its own can be replaced at much lower cost than a complete new pump.
 
you should really be testing the water pressure to see if it exceeds the prv pressure setting via hot water tap with a wet tester that clamps over tap or one that connects on to pipework would be better and then run calorifier till hot and test and check to see what happens if you put readings and pressure differences including time for pressure increase then list here I could prob tell you a possible problem but basically
if standing pressure cold is say 1bar then whilst heating up water expands by by if I remember 1 25th slowly and this in turn should drip through valve in question and then upon temp reaching temp required it should then discontinue to to drip as these valves are meant to drip till expansion has been obtained
well does on my calorifier and it does on all domestic unvented systems and in domestic installation they have a prv/temp relief valve for discharging the water from expansion

so other checks to think about is pump and pressure shut off valve rated to high for your calorifier ie if its 3 bar and a 3bar prv then it will drip as expansion hasn't been taken into consideration off pump data plate

nick

not sure ive xplained good enough but you mite get the gist of what im saying
 
VicS said:
Generally the pressure sensor complete with or even the micro switch on its own can be replaced at much lower cost than a complete new pump.
Click to expand...

Thanks VicS, the old one was as old as the boat so I figured by fitting a new complete unit I could forget it for another 18 years.
 
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