Water Heater Overfilling

[Caliber40]

Interesting thing happened this evening.....my boats fresh water pump would not pump nor shut off. When I open the drain valve on the hot water heater and let some water out the system started working again. So.....was hot water tank over full? If so what causes this.

Thanks in advance

Greg

[sailorchic34]

You can't overfill a water heater. Odds are what happened is there was air at the pump that would not clear the pressure switch. Opening the drain valve, let the air bubble get past the pump.

Could have been something else, but I'm not sure what.

[Herreshoff]

I've got exactly the same thing happening with my hot water cylinder. Bizarre. With mine the hot water cylinder overflow is letting fresh water into my sump. Would be interested in a solution. I will look at this drain valve possibility. Thanks.

[lamadriver]

More than likely what is happening is the pressure relife valve is blowing off hot water, that is ending up in your bilge/

it could be the thermostat or the PRV.

This happened to me I couldn't figure out where the water was coming from in the bilge.

The bottom of the PRV usually has a pull so you can bleed it automaticaly .Pull it up an down a few times make sure it is'nt stuck,

In my case, there was too much pressure in the system. The hot water heater was only rated for X and the fresh water pump was Y. If you have too much PSI in your fresh water system the PRV will keep blowing off. Some pumps will let you regulate the PSI range, i couldn't. I changed the pump and haven't had a problem since.


Hope this helps.

[a64pilot]

That is exactly it, sometimes they are called a T&P valve, temperature and pressure, they are the safety valve that will keep the thing from exploding like a bomb if the thermostat gets stuck and the heater coil stays energized.

[sailorchic34]

The solution to preventing the T&P relief from popping off when a batch of cold water is heated in the tank is to install a expansion tank in the system. That will give a place for the water to expand too.

[Herreshoff]

Hmmm. I'm still having trouble with mine.

I opened the drain valve on the bottom of the hot water cylinder and let about 5 litres out with and without running the pump. This hasn't fixed the problem as of yet.

What's is happening is, when the fresh water pump is switched onto pump switches on and off. Approx, 1second on, 2 seconds off, and repeat. Water then drains from the hot water cylinder overflow pipe into the sump. It might be worth noting that this is happening with or without the cylinder been heated and with the hot or cold taps turned on.
When i kink the hoses coming from the pump to the cylinder the pump stops and everything functions normally again.
Any ideas?

Thanks,

[TeddyDiver]

Originally Posted by Herreshoff

Hmmm. I'm still having trouble with mine.

I opened the drain valve on the bottom of the hot water cylinder and let about 5 litres out with and without running the pump. This hasn't fixed the problem as of yet.

What's is happening is, when the fresh water pump is switched onto pump switches on and off. Approx, 1second on, 2 seconds off, and repeat. Water then drains from the hot water cylinder overflow pipe into the sump. It might be worth noting that this is happening with or without the cylinder been heated and with the hot or cold taps turned on.
When i kink the hoses coming from the pump to the cylinder the pump stops and everything functions normally again.
Any ideas?

Thanks,

What Lamadriver says in post #4. Either the T/P valve or the pump pressure switch adjusted wrong or malfunction..

BR Teddy, plummer in my previous life

[Steven UK]

Leaking pressure relief valve on the tank?

[belizesailor]

Originally Posted by Herreshoff

Hmmm. I'm still having trouble with mine.

I opened the drain valve on the bottom of the hot water cylinder and let about 5 litres out with and without running the pump. This hasn't fixed the problem as of yet.

What's is happening is, when the fresh water pump is switched onto pump switches on and off. Approx, 1second on, 2 seconds off, and repeat. Water then drains from the hot water cylinder overflow pipe into the sump. It might be worth noting that this is happening with or without the cylinder been heated and with the hot or cold taps turned on.
When i kink the hoses coming from the pump to the cylinder the pump stops and everything functions normally again.
Any ideas?

Thanks,

Originally Posted by TeddyDiver

What Lamadriver says in post #4. Either the T/P valve or the pump pressure switch adjusted wrong or malfunction..

BR Teddy, plummer in my previous life

I think youve got a malfunctioning pressure switch and the hot water tank issue is unrelated.

[newhaul]

Sounds like a failing t&p valve to me. ( its also the cheapest part to replace to diagnose the problem)

[a64pilot]

Originally Posted by newhaul

Sounds like a failing t&p valve to me. ( its also the cheapest part to replace to diagnose the problem)

Yep, but first see what the pressure rating is, if it's say 40 PSI and you have 50 PSI water pressure, it's working just like it should.
I believe there are some water heaters that won't take high pressure?

[Herreshoff]

Thanks for the advice teddy. I don't think it is a problem with the water pump ( as belizesailor suggestedas well), for when I kink the pipes leading to the hot water cylinder the pump switches on and off as it should when I use the sink taps. It looks like I might have a faulty t/p valve then. I will replace this and see what happens. For the mean time can you see any problem with blocking the pipes going to the hot water tank until I get the t/p fixed so I stop loosing lots of good fresh water into my sump?

In terms of the pressure rating, it's the same set up as has been used on the boat for 10 years or so which makes me think the pressure ratings are most likely as they should be.

Steven uk, it's not leaking from the valve itself. It's releasing fresh water through a pipe labeled 'tank overflow'.

Thanks for the help.
Niki

[Cheechako]

Air in the system. Cant overfill a hot water heater.

[sailorchic34]

An British clorifiers have a lower working pressure then many newer 12v water pumps. They are made of copper which lasts a long time, but can't take the pressure. A USA water heater is generally constructed to 80-100 psig with a 125 psig relief. A british clorifier might only be rated for 2.5 bar (35 psig) and you might have a 50 psig/4 bar pump. If that is the case either replace the pump or add a Pressure reducing valve before the water heater/clorifier.

Could also be a bad t&P. But verify the pressure rating of the existing one and make sure the new one does not exceed the existing pressure rating.