heater burst a pipe (1 Viewer)

[pappajohn]

i cant see a frost discharge valve in that picture

It's what you just said... They aren't all automatic.
Why would a PRV have a manual lever? It's a safety feature.
Why would a simple air admittance valve need a pipe going through the floor to outside when air in the locker will be cleaner.

 

[mitzimad]

looking at the instructions truama call the red part a breather its purpopse is to allow air into the system if its drained with the taps shutits held closed by water pressure if your pump was running with the prv open that valve would probably drible as it will not have enough water pressure to close it

 

[mitzimad]

It's what you just said... They aren't all automatic.
Why would a PRV have a manual lever? It's a safety feature.[/QUOT
most have a manual lever for draining the system even most domestic ones can be opened manually officially you are supposed to open it as part of a service to ensure its noty stuck closed in the real world no one does because nine times out of ten it will not seal again

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[mitzimad]

the blue item with the yellow handle is not a frost stat in anyway shape of form purely a pressure relief valve i could discharge if the pipework was frozen but that is because there would be a pressure rise if the heat source was activated

 

[hilldweller]

Should that clear pipe that comes out of the floor therefore have been cut on installation allowing one to empty and one to relieve any pressure.
I’ve never emptied it before as it’s new to me.

At last you've got there.

I guess they issue Xmm of clear pipe for the job and some clueless moron did not realise it needed cutting into two pieces, Maybe the easy way to get the lengths right is connect both ends then slice it once finished.

 

[pappajohn]

the blue item with the yellow handle is not a frost stat in anyway shape of form purely a pressure relief valve i could discharge if the pipework was frozen but that is because there would be a pressure rise if the heat source was activated

Shall we start again......

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[Scotch mist]

@mitzimad , makes sense , sounds like , the red tee/ valve is not a air admittance BUT a air intake valve but still needs vented to the outside Incase any water passes through it , the valve on the blue pipe is a drain point with possibly a low temperature relief, if the temperature gets too low the valve opens automatically to let the water out , the red valve opens to allow air in so the tank doesn’t hold a vacuum

Or with papajohns info slightly different , the fix will be the same , either way it needs 2 discharge pipes

 

[gus-lopez]

That’s just what I was typing when you replied, perhaps that’s the way they are installed from new but then cut allowing 2 discharge pipes

prize winner. They install like this so as not to waste pipe. Someone has forgot to cut it.

 

[mark49]

Thanks again to all responses, hopefully it hasn’t knackered the heater, I’ll put it together when I’ve got replacement pipe and fingers crossed.

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[pappajohn]

Something still caused the RED pressure relief valve to open though.

 

[mark49]

I had typed that very question before then thought better of it( taken enough o you’re time)but I do like to know the why’s.
What’s a usual cause of pressure build up that would cause it to do whatever it done.

 

[pappajohn]

My only thought is a faulty/failed internal thermostat.
It will be a none adjustable one pre-set to a maximum temperature... Say 60°c.
Depending how it's failed it either wouldn't work at all or wouldnt switch off at 60°c and continue to heat up.
Only sure way is have it tested.

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[mark49]

I’m not near the heater now,but there is a big button under a slide up cover, it must be to reset something, I’m was going to source Truma info to clarify before pushing.

 

[pappajohn]

Sorry, no idea.

 

[hilldweller]

Something still caused the RED pressure relief valve to open though.

Already been done - expansion in a closed system. Hot tank full, cold. Heat on. Water expands, no-where to go.

The pipe burst where it would be hottest and weakest.

We have the same water heater, on electric the heat was described as "mad hot" and it sure is. It can be set lower on gas. Works a treat.

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[mark49]

That sounds like the explanation I need. Although it was gas only,I’ll change the settings for heat requirements once it’s back together again. Thanks

Already been done - expansion in a closed system. Hot tank full, cold. Heat on. Water expands, no-where to go.

The pipe burst where it would be hottest and weakest.

We have the same water heater, on electric the heat was described as "mad hot" and it sure is. It can be set lower on gas. Works a treat.

 

[hilldweller]

That sounds like the explanation I need. Although it was gas only,I’ll change the settings for heat requirements once it’s back together again. Thanks

Just remembered -- we had a water leak, it was water gushing from that red valve, it just was not tight enough, it's a compression fitting, a bit of a turn and it was sound again.

First the pump is high pressure and second the water expands, so that relief valve is there for good reason.

 

[mark49]

Sounds like it, make sure you’re pipe under the van is not linked and has been cut as the early photograph shows,doesn’t sound like this had anything to do with the original fault but as mentioned, terrible workmanship and lowsy quality control.

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[pappajohn]

Already been done - expansion in a closed system. Hot tank full, cold. Heat on. Water expands, no-where to go.

Sorry Brian, it doesn't work like that.
Like a domestic boiler the tank has an expansion air gap at the top to take account of water expansion as it heats up. As It expands it compresses the trapped air. This why the hot outlet doesn't come out of the top surface of the boiler but slightly lower on the side.
The PRV will ONLY open if the pressure exceeds that of the PRV which is higher than the boiler pressure under normal use
If the stat fails the pressure will eventually exceed the safe working pressure of the vessel and the PRV will open.

 

[tonyidle]

@mitzimad , makes sense , sounds like , the red tee/ valve is not a air admittance BUT a air intake valve but still needs vented to the outside Incase any water passes through it , the valve on the blue pipe is a drain point with possibly a low temperature relief, if the temperature gets too low the valve opens automatically to let the water out , the red valve opens to allow air in so the tank doesn’t hold a vacuum

Or with papajohns info slightly different , the fix will be the same , either way it needs 2 discharge pipes

It simply needs the loop under the floor cutting: two separate pipes, both drain & PRV work as they should.

Sorry if I offended you or anyone else with a previous, rather frustrated, post. I hope I made at least one reasonable point which is that all keyboard warriors are connected to t'internet wherever they are. Otherwise they could not access this Forum so either the person asking the question, or any one of those answering, could have definitive information at their fingertips within minutes. Incorrect information and arguments about what is correct information simply serve to confuse. My remark about searching for manuals wasn't aimed at you or the OP in particular it was really a frustrated observation. Label me a smart ar*e if you wish but I carry every bit of information available on everything in my van on a tablet - for the same reason that many insist on carrying a spare wheel. Motorhome equipment failure and punctures never occur at a convenient time or location. I didn't see the photo with the looped pipe until @pappajohn pointed it out.

 

[tonyidle]

Sorry Brian, it doesn't work like that.
Like a domestic boiler the tank has an expansion air gap at the top to take account of water expansion as it heats up. As It expands it compresses the trapped air. This why the hot outlet doesn't come out of the top surface of the boiler but slightly lower on the side.
The PRV will ONLY open if the pressure exceeds that of the PRV which is higher than the boiler pressure under normal use
If the stat fails the pressure will eventually exceed the safe working pressure of the vessel and the PRV will open.

That's only true if the water heater has not been in continuous use and the air hasn't dissolved in the water. ISTR (and I'm not going to look it up ) that Truma recommend draining after a certain (fairly short) period to re-establish the air cushion,

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[rangi]

@ papajohn knows what he's talking about, never known him to give bad advice, I know who's advice I'd follow.

 

[tonyidle]

@ papajohn knows what he's talking about, never known him to give bad advice, I know who's advice I'd follow.

He might not see your complimentary post. @pappajohn
He will now .

 

[pappajohn]

It simply needs the loop under the floor cutting: two separate pipes, both drain & PRV work as they should.

A problem Tony, the pipe has burst above floor.
So yes, one half to the dump valve will be OK if cut underneath, which is good looking at all that crap slapped around the pipe as it enters the floor, but it still needs renewing to the PRV.

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[Misterg]

The red elbow is described in our installation instructions as "elbow fitting with integrated ventilating valve" (i.e an air admittance valve) it later says that it must be used "to guarantee complete emptying of the water content".

The blue valve with a yellow handle is described as "safety (pressure relief) drain valve" (i.e. a combined drain / PRV & possibly frost valve).

(It goes on to say: "Pressures of up to 4.5 bar can occur in the safety/drain valve ... because of the heat of the water and the resulting expansion." - nothing about air cushions, etc which I don't believe it has.)

The vent hose on the elbow ("venting hose, external diameter 11 mm") is smaller than the outlet of the drain/prv valve which is supplied with a short (~6") length of the correct diameter clear hose (~15mm), so it hasn't been looped by accident - my guess is that someone has bunged one into the other as a means of stopping the frost valve draining the system at some point, effectively sealing the system.

No matter - both hoses need to end in open ends under the van. There may or may not be a problem with the boiler which has caused the problem, or it might just have been pressure build up from the normal expansion as the boiler heats up that has done for the hose - maybe over several heating cycles.

The red elbow has a one way valve in the air connection, so the water that has come out has most likely come from the blue valve

The first thing is to replace / repair the hose and make sure that both the red and the blue fittings have an open-ended hose under the van.

 

[pappajohn]

The red elbow is described in our installation instructions as "elbow fitting with integrated ventilating valve" (i.e an air admittance valve) it later says that it must be used "to guarantee complete emptying of the water content".

The blue valve with a yellow handle is described as "safety (pressure relief) drain valve" (i.e. a combined drain / PRV & possibly frost valve).

(It goes on to say: "Pressures of up to 4.5 bar can occur in the safety/drain valve ... because of the heat of the water and the resulting expansion." - nothing about air cushions, etc which I don't believe it has.)

The vent hose on the elbow ("venting hose, external diameter 11 mm") is smaller than the outlet of the drain/prv valve which is supplied with a short (~6") length of the correct diameter clear hose (~15mm), so it hasn't been looped by accident - my guess is that someone has bunged one into the other as a means of stopping the frost valve draining the system at some point, effectively sealing the system.

No matter - both hoses need to end in open ends under the van. There may or may not be a problem with the boiler which has caused the problem, or it might just have been pressure build up from the normal expansion as the boiler heats up that has done for the hose - maybe over several heating cycles.

The red elbow has a one way valve in the air connection, so the water that has come out has most likely come from the blue valve

The first thing is to replace / repair the hose and make sure that both the red and the blue fittings have an open-ended hose under the van.

@Misterg Go back and look at the pictures and descriptions in post #36.

 

[Misterg]

Go back and look at the pictures and descriptions in post #36.

@pappajohn - I did read them, but they're misleading / shorthand convenience stock descriptions, hence my post above. The red elbow is a one-way air admittance valve so that the boiler can drain when the "safety (pressure relief) drain valve" opens. Arguable it could be called a pressure relief valve, but 'vacuum relief valve' would be more accurate. It *isn't* an over pressure relief valve (as one would normally expect when the term PRV is used - that function is part of the blue valve).

I have held both in my hands and fitted them to our van and can confirm that there is no mechanism for over-pressure relief in the red elbow - there's just a check valve in the air connection on it.

If the OP corrects the hoses they can fill / fire up the boiler again under close supervision and see if there is still a problem.

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[mark49]

@Misterg you say the water probably came from the blue valve,but it was hot water that was coming out if this makes any difference.

 

[mitzimad]

The red elbow is described in our installation instructions as "elbow fitting with integrated ventilating valve" (i.e an air admittance valve) it later says that it must be used "to guarantee complete emptying of the water content".

that's what i said

The blue valve with a yellow handle is described as "safety (pressure relief) drain valve" (i.e. a combined drain / PRV & possibly frost valve).

there is nothing in the blue valve that is temperature sensing

i thought the looped pipe was on a different van but i suspect what has happened is the yellow lever has been lifted and pressurised the thin plastic looped drain of hose causing it to burst
the question is was it lifted manually or did it open due to internal pressure i suspect it was opened manually as pressure release wouldn't move it to the upright position which is locked open position for draining

 

[hilldweller]

I have held both in my hands and fitted them to our van and can confirm that there is no mechanism for over-pressure relief in the red elbow - there's just a check valve in the air connection on it.

Thank you, I hate being wrong but I'm always willing to learn.

But I'm puzzled, if it is just letting air in then in reality it does not need a pipe to the outside. The other end of the that looped pipe will be blocked by the manual dump valve. So what popped the pipe open ?

AH!! The dump valve could be open, naturally it would dump nothing but it would mean both sides of the red valve would have equal pressure on it, for what that's worth ???


This confirms "breather" not pressure relief:
https://www.caravanaccessoryshop.co...astore-elbow-push-fit-with-breather-pipe/3248

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