On 17/02/2021 16:03, newshound wrote:
On 17/02/2021 07:55, The Natural Philosopher wrote:
On 16/02/2021 21:53, newshound wrote:
On 16/02/2021 21:35, S Viemeister wrote:
On 16/02/2021 20:35, Chris B wrote:
Friend of mine has a leaking HW cylinder.Â* They have a very
expensive maintenance contract with BG so they have rung them up to
come and have a look at it.

"Oh you have got a very funny tank - its got 2 coils in it."

"Yes we know it has 2 coils, one is for the Gas the other is for
the back boiler behind the open fire in the lounge."

"It will take us ages to get hold of a cylinder of that size with 2
coils can you live without the back boiler?"

"Well yes its never been used since the gas was installed."

My question to the group, if you drain all the water out of a back
boiler system, does that preclude using the open fire?Â* IE will you
melt/damage/distort the fireplace/boiler?

I don't think it will bother them if the answer to the question is
no you cant use the fire - as it has not been used in 25 years -
but they would like to know if it MUST not be used rather than they
choose not to use it.

MUST not be used, unless made safe first.

http://www.heatingandventilating.net/womans-death-in-boiler-explosion-highlights-back-boiler-risk

The issue there was that the pipework had been capped and there was
presumably still some water left in the back boiler. Very bad idea.

As the other poster said, filling with sand AND LEAVING VENTED is
traditional, although TBH I am not quite sure what the sand filling
does.

Square root of Sweet Fanny Adams, in reality. It probably helps to
spread the het evenlly prevednting hot spots

It's not going to conduct particularly efficiently, and will stop
convection!


Â*Â*My woodburner is just a cast iron box; no firebricks so the back
panel sees direct heat. With a back boiler, it's the front face of
the boiler that sees direct heat. Its back face will get up to a
similar temperature by radiation, depending on how well it is cooled
from behind. You are not going to melt anything in a woodburner,

I beg to differ. I've melted grates...

although in a coal stove (especially with smokeless fuel) the grate
may get hot enough to distort significantly.

And in an openÂ* wood fire. I can show you if you like. In the end
burning coal or charcoal is no different temperature wise

Wow, you must have had a hell of a draft (assuming it was a CI grate).
With a stove, wood does not need to be on a grate IME

dunno really - nothing special. My wood burner DOES have a CI grate - a
new one - the last one burned and cracked






If it were mine, and if I was unable to confirm with high confidence
that the pipework had not been capped (and perhaps bricked in) then I
would probably drill a few 3/8 inch holes in the boiler through the
open door. It should drill reasonably easily with a cordless drill
and a sharp HSS drill bit. Come to think of it, a couple of
through-wall slits with an angle grinder would have the same effect.

Well there is access to the pipework at the tank isn't there? Simply
leave it open

If you cant disconnect more locally

IIRC most gravity fed systems also have a pressure valve to prevent
blowing up.

In short you really have to be a total arse and not only disconnect
the pipework but cap it at the fire itself to blow the **** up.


Which is what I assume happened in the quoted case. It's easy enough to
imagine how all the visible iron pipework might be removed when an older
house is updated by adding an immersion or a gas boiler of some sort. As
you say, only a complete idiot would cap the boiler at the same time.

Well that is plumbers for you. Generally reckoned to be the thickest of
all the trades






--
A lie can travel halfway around the world while the truth is putting on
its shoes.