water pump relief valve

[chrism1]

hi been noticing water in my bilge and when the water pump is on it by-passe with a small discharge into the bilge. upon investigation i niticed a relief valve attached to the hot water cylinder in the engine bay. with this it has the flow and return from the engine and also a adjustable relief valve? if turned it disharges continually and if adjustated the other way it discharges when the water pump is engaged. anyone got any ideas is this correct or is it fulty. i believe it shoud'nt always discharge when the pump is working!!!! any info would be a great help

 

[discovery2]

It sounds as if you are referring to the pressure relief valve, which I understand is an essential component in the hot water system. It is designed to reduce the pressure build-up as the water is heated (and expands), resulting in a small amount of water being ejected. On my boat, I have placed a length of reinforced PVC pipe from the valve to a small overboard skin fitting. Any leaking water (which could be very hot) is ejected over the side and not in the bilges.

However, I note you say that some water is discharged when the water pump is operating. This may suggest to me that either the water pump pressure is too great, or the valve is faulty and needs replacing.

Hope this is of some help, however, other contributors may well have other suggestions!

Good luck
David

 

[chrism1]

thanks for the info, can you tell me is the pump adjustable. if so i take it located on the pump somewhere. i like the idea of the extended hose

regards

 

[discovery2]

Not sure if the pump pressure can be adjusted, but if so, probably will be on the pump! If you can give the make/model of the pump I may be able to help further.

David

 

[nedmin]

Is your pump cutting out?it should do when it gets up to pressure.Is the pressure out the taps more than usual?If so it could be the pressure cut out switch which is either on the end of pump,or in the pipe work near pump not working properly,they are usually a micro switch operated by a plunger backed up by an adjustable spring.The pressure relief valve on top of calorifier operates on a cam,when you turn part way it opens the valve to allow you to breathe air out of cylinder on filling for first time .they are usually rated at 4psi.You can get them from Plumb Centre etc there is a rating stamped on them,not very expensive.Why not take off, invert it and put some wwd 40 in it and see if it leaks out the outlet.If all ok put back and problem then pressure relief switch.Dont forget you ALWAYS get some water out the valve on initial warming of cylinder,so its worth putting in an overflow pipe as disc.2 suggests,mine goes out the engine bay inlets.

 

[BlueChip]

I've got the same problem - mine used to vent about 1 litre a weekend which we trapped in a bottle - now its venting about that every few hours. We also find the water pump kicks in momentarily in the night to build the pressure up again. I'm off to the plumbers to pick a new one up now

The problem with venting it overboard is that you would never know when the valve was leaking. It would be quite easy to lose a lot of water and not know. I just bailed about 10 gallons out of the engine bay and thats just a weekends worth. Our tank only holds 50 gallons - would be horrible to be half way across the channelor at anchor somewhere and not to be able to make a cup of tea