Powermax 155x

[Onetap]

How can a leaking Plated heat exchanger cos loss of pressure in a central heating system

Do you really need someone to explain that?

Yes, I'm afraid that you probably do.

Could you explain what a heating pressure loss has to do with the gas train, Mr. Corgiman?

Also are you going to apologies for that terrible slur you laid at me on a previous post onetap?

What slur? Do you mean this?

//www.diynot.com/forums/viewtopic.php?p=791989#791989

There is no slur. You used a post about a gas explosion to give out about DIY gas work. You do not know what happened, so I'd be really grateful if you'd belt up until you know better.

There have been plenty of accidents caused by gas "professionals"; too many of them are ignorant of engineering fundamentals, as your question above shows. When there is a mishap, they are very experienced in evading liability.

Corgi and it's members are not a part of the solutions, they have a conflict of interests and have added to the problems.

 

[corgiman]

Central heating pressure 1 bar nominally

water main pressure 3 bar with pressure reducing valve and I would not expect a drop of 2.5 bar during draw off

how does 1 bar leaking into that?

As for the other post I didnt mention on once DIY'ers I was pointing out that the newsreader stated that it was the belief of the chief fire person that the occupier of the property was inspecting his boiler before the explosion occured, so I pointed out that if you are not competant to do so you should leave gas alone!

Not once did I use that post to stick it DIY'ers in particular as you pointed out!


As point I was trying to point out that the range powermax is a terribly dangerous boiler and that someone with out appropriate training would be well advised to leave alone, whether the "gas train" (what ever that means) is touched or not.

Just to point something out to you Onetap this is a public forum and those who post on it are entitled to an opinion whether it is listened to or not, My opinion is that any one who doesnt know this boiler should leave it well alone.

other opinions may differ and it is up to the OP to decide WHAT advice he/she follows.

Great country aint it

 

[Onetap]

how does 1 bar leaking into that?

Plate heat exchanger, high resistance.
Scaled-up plate heat exchanger, huge resistance.
Mains pressure 3 bar, no PRV.
Heating pressure 1 bar cold, 1.5 bar or 2 bar hot, 'cos they're running the hot tap. 3 bar in this example.
Static pressure in the DHWS with the tap off is 3 bar.
Static pressure on the downstream end of scaled-up, perforated, plate heat exchanger, 0.5, 0.3 bar, when the HW tap is running.
Boiler at 3 bar, gradually empties into the DHWS.
Turn tap off, heating pressure goes back up. To 3 bar.

As for the other post I didnt mention on once DIY'ers I was pointing out that the newsreader stated that it was the belief of the chief fire person that the occupier of the property was inspecting his boiler before the explosion occured, so I pointed out that if you are not competant to do so you should leave gas alone!

Hearsay; and that would have caused a gas explosion?
You didn't comment on the "few days". Let us hope that the facts are established at the inquest.

Have you ever been to a coroner's court?
There is no one there who is responsible for cross-examining the witnesses in order to established what happened. And if the appropriate questions aren't asked, then the jury, with the limited information available, may make a wrong decision about responsibility for the death(s).

Great country aint it

No.

 

[corgiman]

You said "Mains pressure 3 bar, no PRV. "

How do you know the static Mains pressure of the OP's mains supply? how could you have possibly checked it? also All the range PM i have worked on have had a Pressure reducing valve fitted as part of the pack? bit of a job to remove them so how do you know it has been removed on this one?

you said "Plate heat exchanger, high resistance" "Scaled-up plate heat exchanger, huge resistance."

Against what?


"Static pressure on the downstream end of scaled-up, perforated, plate heat exchanger, 0.5, 0.3 bar, when the HW tap is running"

As Oll says this could happen, but the OP says the pressure drops to 0 and doesnt say that it goes back up? also says that the pressure doesnt equalise.

FYI I have no idea why its doing this, and unlike some on this here wonderful sight I cannot perfectly fault find over the net and need to "lock horns" with a boiler sometimes.


Hearsay; and that would have caused a gas explosion?
You didn't comment on the "few days". Let us hope that the facts are established at the inquest.

Have you ever been to a coroner's court?
There is no one there who is responsible for cross-examining the witnesses in order to established what happened. And if the appropriate questions aren't asked, then the jury, with the limited information available, may make a wrong decision about responsibility for the death(s).

I agree with you it is heresay now I think of it and i maybe should not have posted the reporters view in its entirity.

And yes I have been in coroners court many times and, as much as I hate to admit it, I should have know better you are right I should not have opiniunated so early or repeated what the reported stated

Dammit I hate it when I get it wrong goddamyou and I submit my apologies for that but I was not using it to have a pop at DIY'ers and nor would I use such a tragic death to make to score some cheap points for CORGI. And I still resent your comments stating that this was my sole aim.

PS and other than the over regulation and the big brother attitude of our government this IS a great country

 

[Onetap]

The mains pressure is good and have tried changing the calorifier already. Any ideas?

What do you mean by calorifier? The plate heat exchanger inside the boiler, or is there a domestic hot water storage cylinder?

You said "Mains pressure 3 bar, no PRV. "

How do you know the static Mains pressure of the OP's mains supply?

We don't know; you had suggested 3 bar mains pressure in your earlier post of 11:22 p.m., so I was just putting in some of the other possible numbers as a 'for example' exercise.

 

[ollski]

What do you mean by calorifier? The plate heat exchanger inside the boiler, or is there a domestic hot water storage cylinder?

I take it to mean the 26 plate external heat exchanger.

 

[Onetap]

I take it to mean the 26 plate external heat exchanger.

So did I, but I've never heard it called a calorifier; DHWS storage cylinders are often called calorifiers.

A combi with a DHWS cylinder is unusual, but quite possible.

 

[davejones72]

Sorry, by calorifier I am meaning the plate heat exchanger. Thanks for all the suggestions.

 

[Balenza]

davejones wrote

The mains pressure is good and have tried changing the calorifier (plate heat exchanger) already. Any ideas?

Never mind Onetap, we all get it wrong from time to time.

Onetap wrote

Mains pressure 3 bar, no PRV.
Heating pressure 1 bar cold, 1.5 bar or 2 bar hot, 'cos they're running the hot tap. 3 bar in this example.
Static pressure in the DHWS with the tap off is 3 bar.
Static pressure on the downstream end of scaled-up, perforated, plate heat exchanger, 0.5, 0.3 bar, when the HW tap is running.
Boiler at 3 bar, gradually empties into the DHWS.
Turn tap off, heating pressure goes back up. To 3 bar.

Interesting . Complete twaddle but interesting none the less.

The OP stated the primary side dropped to zero pressure.
"0 bar" I believe.

If the plate was perforated then when the system is static this would allow flow into the primary side to whatever pressure is in the secondary side and I am sure it would be above zero.

 

[corgiman]

"We don't know; you had suggested 3 bar mains pressure in your earlier post of 11:22 p.m., so I was just putting in some of the other possible numbers as a 'for example' exercise."

Eh?

I dont understand what you are getting at here?

I was working on the assumption that the pressure reducing valve had notbeen removed and had been set at 3 bar as per MI's

You said 3 bar no PRV

I took that to mean that you knew that the mains standing pressure was 3 bar, hence why I asked how do you know?


Balenza "If the plate was perforated then when the system is static this would allow flow into the primary side to whatever pressure is in the secondary side and I am sure it would be above zero."

Thats what I thought too, that and the fact that the pressure in the boiler would whack upto 3 bar as soon as the tap was turned off.

I still havent the foggiest why its doing what its doing though? unless its over expanding and triggering the pressure reducing valve, but that wouldnt explain why it drops to 0 while its running

this is a dilly of a pickle

 

[Onetap]

davejones wrote

The mains pressure is good and have tried changing the calorifier (plate heat exchanger) already. Any ideas?

You lie; he did not write that. You have inserted "plate heat exchanger".

He said he'd changed the calorifier
And what is a calorifier? It is one of these;
http://images.google.co.uk/images?hl=en&q=calorifier&gbv=2

Well, it's a hot water storage cylinder and not a plate heat exchanger. The word isn't much used in respect of domestic systems, so you wouldn't have known what it means.

Onetap wrote

Mains pressure 3 bar, no PRV.
Heating pressure 1 bar cold, 1.5 bar or 2 bar hot, 'cos they're running the hot tap. 3 bar in this example.
Static pressure in the DHWS with the tap off is 3 bar.
Static pressure on the downstream end of scaled-up, perforated, plate heat exchanger, 0.5, 0.3 bar, when the HW tap is running.
Boiler at 3 bar, gradually empties into the DHWS.
Turn tap off, heating pressure goes back up. To 3 bar.

Interesting . Complete twaddle but interesting none the less. ?

Not twaddle, it is exactly what happens when a heat exchanger fails. Water flows from the high pressure to the low pressure side until the pressures equalize. The flow rate is determined by the pressure differential and the size of the hole(s).

It is a hypothesis and the OP could easily devise a simple test to prove or disprove it. I'd turn off the power to the boiler, isolate the mains water supply and open the hot tap. I still think it's probably a failed heat exchanger.

The OP stated the primary side dropped to zero pressure.
"0 bar" I believe.

If the plate was perforated then when the system is static this would allow flow into the primary side to whatever pressure is in the secondary side and I am sure it would be above zero.

Where did he say it stayed at 0 bar pressure?
Oh, he didn't.

Of course, my hypothesis above could be wrong.

Can you suggest a more plausible explanation, Balenza, instead of sniping with your silly criticisms at those who do put forward an explanation?

No?

Best if you just shut up then.

 

[Onetap]

I was working on the assumption that the pressure reducing valve had notbeen removed and had been set at 3 bar as per MI's

There was no pressure reducing valve supplied with the Powermax. The DHWS was rated to 6 bar working pressure. The manufacturer's recommendation was that if the mains pressure was above 6 bar, then "pressure reduction to between 2 to 3 bar is recommended for splash free tap operation."

I still havent the foggiest why its doing what its doing though? unless its over expanding and triggering the pressure reducing valve, but that wouldnt explain why it drops to 0 while its running

It happens when the hot tap is run, which would cool the store down.

It might well be that the expansion vessel has failed and there's no air in it.

When the hot tap was run, the primary water in the thermal store would cool and contract as the stored heat was lost. If there was no air charge to absorb the expansion, a small contraction of the water would cause a large primary pressure drop.

See that, Balenza? Another plausible, thought-out hypothesis.
Have you come up with any suggestions yet?
No?
Never mind.

 

[corgiman]

So why when the tap is closed does the water pressure in the boiler not go up?

 

[Onetap]

So why when the tap is closed does the water pressure in the boiler not go up?

I don't recall the OP saying it didn't go up.

If it is a failed PHX, the pressure would start going up gradually as soon as you closed the tap.

If it was the expansion vessel, the pressure would start to go up as the 100 litres of water in the thermal store heated up and expanded again.


So, if you'd turned off the power to the boiler, and isolated the mains water supply, a loss of pressure on opening the hot tap AND pressure recovery on repressurizing the DHWS, would indicate the PHX had failed.

If not that, then with the power on (to operate the DHWS pump) and the gas off, a pressure loss on running the DHWS AND no pressure recovery until the boiler had been heated up again, would suggest the expansion vessel.

PS, But then, in the latter case, the low pressure would operate the LP lock-out, so you'd have to put in some cold water to get it to fire. If the expansion vessel has gone, the excess water would get discharged from the safety valve as it heated up and expanded. Probably simpler just to check the expansion vessel; you have to depressurize the system to do that. They're often undersized on the Powermax because installers don't take account of the 100 litres in the thermal store.

 

[corgiman]

So why when the tap is closed does the water pressure in the boiler not go up?

I don't recall the OP saying it didn't go up.

.

And I dont recall saying it did

maybe he can clarify