Hot water system

[Sessa Lel]

Hi
Ok, I went to the boat today, just to recap, I have cold water at 3 taps (pump working) I have no hot water pressure from any of the 3 hot taps, no pump at all.
I turned the valve on the hot water tank by 1/4 turn (sprung valve, if you go to far it goes back to starting position) while keeping valve turned the pump comes on for approx 10 seconds, then stops. check hot water taps, loads of pressure for approx 10 seconds then water stops flowing.
so today I turned on cold water in toilet (pump working) turned hot water in kitchen sink no pressure. with my limited knowledge of plumbing, if the hot water turned on, cold water would go into hot water tank to replenish the hot water being delivered to tap, (that's how it works on house plumbing, but tank is feed by cold water gravity through the bottom pushing hot water out of the top to taps) so can't work out why the pump does not work with hot tap open! So my questions are, what is the valve on the tank? why when turning does it make the pump work? why does the pump not work when hot water tap on (I presume pump should work)
today I also turned on all the hot water taps for at least 1hr (I just could not see how that would work as pump not pumping) and I also brimmed the cold water tank as suggested by someone on this forum.
Thanks in anticipation

 

[XPS]

Hi
Ok, I went to the boat today, just to recap, I have cold water at 3 taps (pump working) I have no hot water pressure from any of the 3 hot taps, no pump at all.
I turned the valve on the hot water tank by 1/4 turn (sprung valve, if you go to far it goes back to starting position) while keeping valve turned the pump comes on for approx 10 seconds, then stops. check hot water taps, loads of pressure for approx 10 seconds then water stops flowing.
so today I turned on cold water in toilet (pump working) turned hot water in kitchen sink no pressure. with my limited knowledge of plumbing, if the hot water turned on, cold water would go into hot water tank to replenish the hot water being delivered to tap, (that's how it works on house plumbing, but tank is feed by cold water gravity through the bottom pushing hot water out of the top to taps) so can't work out why the pump does not work with hot tap open! So my questions are, what is the valve on the tank? why when turning does it make the pump work? why does the pump not work when hot water tap on (I presume pump should work)
today I also turned on all the hot water taps for at least 1hr (I just could not see how that would work as pump not pumping) and I also brimmed the cold water tank as suggested by someone on this forum.
Thanks in anticipation

The sprung valve is a pressure relief valve on the tank to deal with an over pressure of the hot water tank, when you turn it then you should see water coming out of the valve and into the bilge.

Or has someone incorrectly connected the hot water supply to this valve ?

 

[Sessa Lel]

With my (amateur) plumbing hat on, trapped air will rise to the highest point in the system. In a badly designed system, that could be in a pipe run that goes over an obstruction and in so doing ends up being the highest point in the system. On a pumped system, this shouldn't happen since the pump will push everything out, air and water. Unless the pump itself has air in it or there's air on the inlet side pipework. There should be a bleed valve on the pump, but it's not always guaranteed. Air in a pump will manifest in cavitation noises from the pump.

I'm still scratching my head over the PRV open, pump stopped scenario. @Sessa Lel says that after the pump stopped and the valve was closed, hot water rushed out at high pressure. I can't see how this is possible with a PRV fully open and the pump stopped. Are we sure this is a PRV?

Hi
Ok, I went to the boat today, just to recap, I have cold water at 3 taps (pump working) I have no hot water pressure from any of the 3 hot taps, no pump at all.
I turned the valve on the hot water tank by 1/4 turn (sprung valve, if you go to far it goes back to starting position) while keeping valve turned the pump comes on for approx 10 seconds, then stops. check hot water taps, loads of pressure for approx 10 seconds then water stops flowing.
so today I turned on cold water in toilet (pump working) turned hot water in kitchen sink no pressure. with my limited knowledge of plumbing, if the hot water turned on, cold water would go into hot water tank to replenish the hot water being delivered to tap, (that's how it works on house plumbing, but tank is feed by cold water gravity through the bottom pushing hot water out of the top to taps) so can't work out why the pump does not work with hot tap open! So my questions are, what is the valve on the tank? why when turning does it make the pump work? why does the pump not work when hot water tap on (I presume pump should work)
today I also turned on all the hot water taps for at least 1hr (I just could not see how that would work as pump not pumping) and I also brimmed the cold water tank as suggested by someone on this forum.
Thanks in anticipation

The sprung valve is a pressure relief valve on the tank to deal with an over pressure of the hot water tank, when you turn it then you should see water coming out of the valve and into the bilge.

Or has someone incorrectly connected the hot water supply to this valve ?

Hi
if you look at the photo looks like cold water going into side of valve, I presume other end goes straight into tank. I have just bought the boat, so now beginning to wonder my self if someone has played with it. I may have to speak to someone who could come and have a look to see if all plumbed ok.

 

[Clash]

Ok, that red cap (presumably what you're twisting) looks very like a PRV to me. Can't see the bottom of it, but I assume it's connected to the hot water tank at that point.

The pipe coming out to the right of the PRV is normally where the over-pressure water is expelled. In your case, without being able to see where it goes, I'm assuming goes into the bilge to be pumped out of the boat. This is the normal setup for those types of PRVs.

More assumptions here. The large pipe with the two jubilee clips on it could be the hot water out from the tank. I'm assuming this as it seems to be lagged. I could be wrong and it's just a large flexible pipe. The red pipe above it is impossible to identify, could be cold water in.

There are other pipes there I can't identify, but there's one there that looks the same as the one coming out of the tank. Could be cold water supply and not hot as I assumed above.

Edit: Looking at the colour of the pipes, they could be coded: red-hot, blue-cold. But that could just be coincidence. If correct, then that red pipe in the foreground could be hot out. Have you felt these pipes to see if they are hot or cold?

 

[XPS]

Hi
Ok, I went to the boat today, just to recap, I have cold water at 3 taps (pump working) I have no hot water pressure from any of the 3 hot taps, no pump at all.
I turned the valve on the hot water tank by 1/4 turn (sprung valve, if you go to far it goes back to starting position) while keeping valve turned the pump comes on for approx 10 seconds, then stops. check hot water taps, loads of pressure for approx 10 seconds then water stops flowing.
so today I turned on cold water in toilet (pump working) turned hot water in kitchen sink no pressure. with my limited knowledge of plumbing, if the hot water turned on, cold water would go into hot water tank to replenish the hot water being delivered to tap, (that's how it works on house plumbing, but tank is feed by cold water gravity through the bottom pushing hot water out of the top to taps) so can't work out why the pump does not work with hot tap open! So my questions are, what is the valve on the tank? why when turning does it make the pump work? why does the pump not work when hot water tap on (I presume pump should work)
today I also turned on all the hot water taps for at least 1hr (I just could not see how that would work as pump not pumping) and I also brimmed the cold water tank as suggested by someone on this forum.
Thanks in anticipationView attachment 186801

Hi
if you look at the photo looks like cold water going into side of valve, I presume other end goes straight into tank. I have just bought the boat, so now beginning to wonder my self if someone has played with it. I may have to speak to someone who could come and have a look to see if all plumbed ok.

It looks like the hot water our is at the top of your photo, the black pipes are from the engine and the blue pipe is cold water in, if you are only getting pressure out of the hot water when you turn the pressure relief valve then something has either seized up in the valve or it has been misconnected.

When you twist the valve can you hear water running into the tank?

I think the valve has been plumbed incorrectly, you can see an arrow which looks to be facing the wrong way for water flow into tank.

 

[Sessa Lel]

Hi
I have a feeling something is not piped correctly, I'm back home now and won't be back at the boat for a couple days. But this time I will look at system to see if all pipes are correctly fitted, never occurred to me it might be a problem with someone messing about with it, I thought it was me not knowing how to get hot water to work.
My first boat and only had it a week.
I know the make of the boiler so will speak to them tomorrow and see if they can shed any light.
Thank for you input, will keep you all posted.
Sessa Lel

 

[Seastoke]

I think the above is correct the rubber are to warm the water from the engine, the expansion valve ie the red one should be on the top pipe hot going out of tank with the arrow pointing to the hot pipe out.

 

[Seastoke]

Did you have the boat surveyed.

 

[Clash]

It looks like the hot water our is at the top of your photo, the black pipes are from the engine and the blue pipe is cold water in, if you are only getting pressure out of the hot water when you turn the pressure relief valve then something has either seized up in the valve or it has been misconnected.

When you twist the valve can you hear water running into the tank?

I think the valve has been plumbed incorrectly, you can see an arrow which looks to be facing the wrong way for water flow into tank.

The arrow on the PRV is to show the direction of expelled over pressure water. I have one almost identical to that in my kitchen on my heating boiler. The only thing that should be connected to that is a pipe to redirect (what would normally be high pressure scalding hot water) in a safe direction. Shouldn't really be an elbow there either.

If you're right and that was plumbed as cold water in, that's really bad. Water can't flow in unless the PRV is open which is mad. That red knob is for test purposes only and the valve is there for safety purposes.

@Sessa Lel The thing to do is trace that blue pipe as far as you can. If you can't follow it from the tank, try from the bilges. You may need someone to watch to see if water flows into the bilges when the PRV is open. If it's as @XPS says, then the pipe should trace to the main water tank. Which is nuts nuts nuts.

The other thing you could do is feel around for hot (even warm) pipes coming from the tank and if the tank itself is warm when the water heater is on. You should be able to identify the cold in and hot out.

 

[Sessa Lel]

Did you have the boat surveyed.

yes, there was no mention of hot water!!!

 

[Clash]

Just so you're sure, here's a photo of my PRV as mentioned above. Clearly very similar to yours. Including the arrow.

 

[Sessa Lel]

I think the above is correct the rubber are to warm the water from the engine, the expansion valve ie the red one should be on the top pipe hot going out of tank with the arrow pointing to the hot pipe out.

 

[Sessa Lel]

 

[Clash]

View attachment 186803View attachment 186804View attachment 186805

That's clear enough. You can see there's a normal butterfly valve on the cold water in. Some loon has put a PRV on there instead. If you were going to install a PRV it should be on the hot side, not the cold. But at least you can see that the hot and cold connectors on the tank are colour coded, so that should be easy to establish.

So (assuming the above is correct - we can't see the tank connections) you need to take that PRV off and replace with a butterfly valve.

 

[Sessa Lel]

Hi
if you look at the photos, that is the same boiler as mine, the diagram shows cold water going into PRV, then look at my photo the arrow, surely that arrow is pointing the wrong way! also, mine is not the original PRV, so has someone fitted the wrong one?
I think by me turning the valve it is opening to let cold water in the stops when tank is full, then hot water flows for 10 secs, and as no water is going through valve there is no flow, hence no pump and no hot water, I'm 99% sure that is the issue.

 

[Sessa Lel]

That's clear enough. You can see there's a normal butterfly valve on the cold water in. Some loon has put a PRV on there instead. If you were going to install a PRV it should be on the hot side, not the cold. But at least you can see that the hot and cold connectors on the tank are colour coded, so that should be easy to establish.

So (assuming the above is correct - we can't see the tank connections) you need to take that PRV off and replace with a butterfly valve.

Some loon haha, I spoke to guy I bought it from, who said he never used hot water!!! haha what a loon

 

[Sessa Lel]

The arrow on the PRV is to show the direction of expelled over pressure water. I have one almost identical to that in my kitchen on my heating boiler. The only thing that should be connected to that is a pipe to redirect (what would normally be high pressure scalding hot water) in a safe direction. Shouldn't really be an elbow there either.

If you're right and that was plumbed as cold water in, that's really bad. Water can't flow in unless the PRV is open which is mad. That red knob is for test purposes only and the valve is there for safety purposes.

@Sessa Lel The thing to do is trace that blue pipe as far as you can. If you can't follow it from the tank, try from the bilges. You may need someone to watch to see if water flows into the bilges when the PRV is open. If it's as @XPS says, then the pipe should trace to the main water tank. Which is nuts nuts nuts.

The other thing you could do is feel around for hot (even warm) pipes coming from the tank and if the tank itself is warm when the water heater is on. You should be able to identify the cold in and hot out.

I think I've sorted it, someone has put a PRV on to cold water inlet, should be a butterfly relief valve, The guy I bought it from when asked about hot water said he never used the hot taps!!!!

 

[Seastoke]

I think the red one is a temperature relief valve which should be on the hot out at the top , it looks like there was a PRV on the inlet to the tank prv pressure relief valve is normally adjustable set to tank spec. I would get a shipwrights to check it .

 

[Seastoke]

Some loon haha, I spoke to guy I bought it from, who said he never used hot water!!! haha what a loon

He is a liar.

 

[Clash]

I think I've sorted it, someone has put a PRV on to cold water inlet, should be a butterfly relief valve, The guy I bought it from when asked about hot water said he never used the hot taps!!!!

Yeah, that's what I said above. A few times. A PRV is a safety valve and has no place as an inlet valve.