In an earlier contribution to this discussion,
Geronimo W. Christ Esq wrote:

Set Square wrote:

From reading the other posts in this thread, I'd say that you have a
conventional boiler with a very *unconventional* hot water system!

I have been carefully reading the FAQ entry about combination boilers.

I assume I am right in believing that all of the hot water sources
(bath tap, shower, and kitchen hw tap) are fed off a specific water
circuit coming from the cylinder. If so, am I right in saying that
provided the existing plumbing is up to scratch, installing a combi
would simply be a matter of removing the existing boiler, cylinder
and loft apparatus, and running a flow/return from the combi's
secondary heat exchanger into the circuit formerly supplied by the
cylinder, and leaving the existing CH circuit pretty much as-is ?

I rather fear that that would result in throwing out the baby with the
bathwater!

It would be a relatively small job to add proper controls to your existing
system - so why throw away a perfectly good boiler.

What you suggest would work provided you have an adequate cold water supply
*and* adequate gas supply (the required power output of a combi is
determined by its "instant" water heating capacity - and is generally
greater than that of a conventional boiler - sized on its space heating
capacity - so it needs a fat gas pipe). But be aware that many people prefer
the concept of stored hot water for fast bath filling etc.

You're going to be looking at a couple of grand for changing the boiler -
whereas you can get a suitable control pack - which would transform your
system - for as little as 60 quid. See http://tinyurl.com/9vdrj as an
example. I think I would personally spend a bit more than this and go for an
S-Plan system with two 2-port valves rather than a single 3-port valve, and
I would use a programmable room stat. Even so, we're talking less than 200
quid.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

raden wrote:

Sounds good. I'll also try getting something pointy to try to poke the
pin, perhaps if I depress it slightly the spring will be able to push
it up.

No, just do as I said, .. it works. You might need to remove the plastic
nut first.

Rats. This didn't work.

I took the head off so that I could see the pin and the nut surrounding
it, and banged away at it for about 30 seconds, but it didn't budge.

When you said "remove the plastic nut" .. what did you mean ? With the
head off, there is no plastic nut visible. Instead there's a brass nut
which I can easily turn by hand. Turning this obviously makes it move up
and down (and bring the pin closer to the surface of the nut). There's
also a wider nut below which I assume is sealing the valve mechanism
into the pipe.

Is it safe to remove the nut with the hole in it ?

Geronimo W. Christ Esq wrote:

Is it safe to remove the nut with the hole in it ?

Sounds like it ought to be. If you start getting wet put it back PDQ ;-)

--
Cheers,

John.

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John Rumm wrote:
Geronimo W. Christ Esq wrote:

Is it safe to remove the nut with the hole in it ?

Sounds like it ought to be. If you start getting wet put it back PDQ ;-)

I don't fancy that

Plumber's coming tomorrow so we'll know all then. I think this is the
point where the DIY stops and becomes "don't f**k with it", and he'll be
annoyed if he has to clean up after my footerings.

I'll update tomorrow with info on whatever the problem eventually turned
out to be (almost certainly the valve) ..

In message , Geronimo W. Christ
Esq writes
raden wrote:

Sounds good. I'll also try getting something pointy to try to poke
the pin, perhaps if I depress it slightly the spring will be able to
push it up.
No, just do as I said, .. it works. You might need to remove the
plastic nut first.

Rats. This didn't work.

I took the head off so that I could see the pin and the nut surrounding
it, and banged away at it for about 30 seconds, but it didn't budge.

When you said "remove the plastic nut" .. what did you mean ? With the
head off, there is no plastic nut visible. Instead there's a brass nut
which I can easily turn by hand.

I presume that'll be the one, is the pin located in a hole down the
middle ?


Turning this obviously makes it move up and down (and bring the pin
closer to the surface of the nut). There's also a wider nut below which
I assume is sealing the valve mechanism into the pipe.

Is it safe to remove the nut with the hole in it ?

I think, as yours is slightly different, you'll have to do a bit of
intelligent experimentation


--
geoff

On Tue, 03 Jan 2006 00:52:44 +0000, Andy Hall
wrote:

On Tue, 03 Jan 2006 00:20:03 +0000, "Geronimo W. Christ Esq"
wrote:

Set Square wrote:

From reading the other posts in this thread, I'd say that you have a
conventional boiler with a very *unconventional* hot water system!

I have been carefully reading the FAQ entry about combination boilers.

I assume I am right in believing that all of the hot water sources (bath
tap, shower, and kitchen hw tap) are fed off a specific water circuit
coming from the cylinder. If so, am I right in saying that provided the
existing plumbing is up to scratch, installing a combi would simply be a
matter of removing the existing boiler, cylinder and loft apparatus, and
running a flow/return from the combi's secondary heat exchanger into the
circuit formerly supplied by the cylinder, and leaving the existing CH
circuit pretty much as-is ?

That way I would not have to replace the timeclock or any of the
electronics, and I've only two extra pipes to install (and a few to
remove) - sounds like slightly less bother (but more expense) than
installing a three-port valve and controlling electronics. The diagram
suggests that the three-port valve in a combi system is built into the
boiler unit. It is something I think I will consider in the medium term.

I like the concept of a combi - it sounds very efficient. And, I imagine
that the current boilers are also condensers so they have an extra level
of efficiency that way as well.


It may be ideal for your situation considering size and type of house

However, do consider the usual warnings:


- Is the mains cold supply adequate? Measure at the cold tap in the
kitchen. If less than about 20 litres/min, it may well be inadequate
for a mains fed system.

- Take a careful look at HW production rate. The quoted figures of
flow for a 35 degree rise in temperature approximate to what you will
get in total at a shower or into a bath in the winter. Some of the
smaller combis deliver 11-13 litres/min. Are you OK with that for a
shower considering that stored systems can deliver 2-3 times that?
Same for baths. Are you OK with 10-15 mins bath filling time?

You can get larger combis of 15-20 lpm, but they are physically large.
Do you have the space? Note that the rating is not important in the
CH context. If the boiler seems large, it doesn't matter because it
will modulate down to the needed rate.

On the other hand, you may well find the gain in space where the
cylinder and roof tanks are to be very appealing. The important
thing is to do some basic checks and make sure that you select
carefully.

In terms of the hookup, you have described what's involved well. It
may also be necessary to upgrade the gas supply from the meter since
combis normally require at least a 22mm supply pipe.





I have a floor standing Kingfisher ( very old one ) ,10mm piping and
rads with TRV's and a Primatic cylinder a few years ago i had a BG guy
out and he said that the rads and piping and TRV's wouldn't stand up
to it if I got a combi boiler fitted because of the pressure .I
questioned what he was saying as i couldnt see how these fittings
could fail but he was insistent ...I didnt get anyhting changed and
the boiler has lasted ever since altho' has probably cost me loads in
gas costs ..
Was he right in what he said .??





Stuart





Shift THELEVER to reply.

Stuart wrote:

I have a floor standing Kingfisher ( very old one ) ,10mm piping and
rads with TRV's and a Primatic cylinder a few years ago i had a BG guy
out and he said that the rads and piping and TRV's wouldn't stand up
to it if I got a combi boiler fitted because of the pressure .I
questioned what he was saying as i couldnt see how these fittings
could fail but he was insistent ...I didnt get anyhting changed and
the boiler has lasted ever since altho' has probably cost me loads in
gas costs ..

Was he right in what he said .??

Possibly partially right for some situations! (that got enough get out
clauses in it? ;-)

Pipework and TRVs are usually fine at pressure (just think about you
mains water pipes etc).

Rads are also usually fine unless on the last legs - in which case the
pressure change may push them over the edge and you will get pinhole
leaks. However if this is the case they were due to do it anyway - you
just accelerated the process by a few months. For a system treated with
corrosian inhibitor on a regular basis this ought not happen anyway.

Old lockshield valves may weep when the pressure is increased. Having
said that there is no guarentee they will (the ones on my system were
fine when I converted it to sealed operation)

--
Cheers,

John.

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On Wed, 04 Jan 2006 02:17:28 +0000, John Rumm
wrote:

Stuart wrote:

I have a floor standing Kingfisher ( very old one ) ,10mm piping and
rads with TRV's and a Primatic cylinder a few years ago i had a BG guy
out and he said that the rads and piping and TRV's wouldn't stand up
to it if I got a combi boiler fitted because of the pressure .I
questioned what he was saying as i couldnt see how these fittings
could fail but he was insistent ...I didnt get anyhting changed and
the boiler has lasted ever since altho' has probably cost me loads in
gas costs ..

Was he right in what he said .??

Possibly partially right for some situations! (that got enough get out
clauses in it? ;-)

Pipework and TRVs are usually fine at pressure (just think about you
mains water pipes etc).

Rads are also usually fine unless on the last legs - in which case the
pressure change may push them over the edge and you will get pinhole
leaks. However if this is the case they were due to do it anyway - you
just accelerated the process by a few months. For a system treated with
corrosian inhibitor on a regular basis this ought not happen anyway.

Old lockshield valves may weep when the pressure is increased. Having
said that there is no guarentee they will (the ones on my system were
fine when I converted it to sealed operation)

Thx John......IIRC the TRV's and the lockshields were fairly new
anyway at the time .As for the radiators they seemed /seem ok.
What might have been a problem and still would be presumably is that
the system is fed from a cold water tank in the communal loft and did
at one time serve several other flats ( which had hot water cylinders
but now have combis,me being the last one ) so inhibitor isn't used .I
know that any time I've removed a rad it has been filled with black
muck when I've washed it out and I wouldnt want that getting in to any
new boiler if it was only the boiler that was replaced . Powerflush
..?????

Stuart .







Shift THELEVER to reply.

Stuart wrote:

Thx John......IIRC the TRV's and the lockshields were fairly new
anyway at the time .As for the radiators they seemed /seem ok.
What might have been a problem and still would be presumably is that
the system is fed from a cold water tank in the communal loft and did
at one time serve several other flats ( which had hot water cylinders
but now have combis,me being the last one ) so inhibitor isn't used .I

The tank that feeds the hot water cylinders etc would have to be
different from the one that serves as a feed and expansion tank for the
CH - so that would not preclude use of inhibitor.

know that any time I've removed a rad it has been filled with black
muck when I've washed it out and I wouldnt want that getting in to any
new boiler if it was only the boiler that was replaced . Powerflush
.?????

One option certainly. Adding a desludging chemical to the existing
system a couple of weeks before it is decommisioned might be a good
move. Give it all a good flush when the new kit goes in, and fit a
strainer to the return to the boiler to catch any dislodged crap before
it gets into the new boiler.

--
Cheers,

John.

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On Wed, 04 Jan 2006 11:45:53 +0000, John Rumm
wrote:

Stuart wrote:

Thx John......IIRC the TRV's and the lockshields were fairly new
anyway at the time .As for the radiators they seemed /seem ok.
What might have been a problem and still would be presumably is that
the system is fed from a cold water tank in the communal loft and did
at one time serve several other flats ( which had hot water cylinders
but now have combis,me being the last one ) so inhibitor isn't used .I

The tank that feeds the hot water cylinders etc would have to be
different from the one that serves as a feed and expansion tank for the
CH - so that would not preclude use of inhibitor.


It's a single feed Primatic I have so the cold water going in from
this tank in the attic fills the HW Cylinder and that serves both the
CH and DHW ( in my flat anyway as the others ,as I said,have had the
cylinders replaced and combis installed ) .The only other pipes
connected to the cylinders are the DHW outlet and an expansion vent
which goes back up to either the roof or the attic where it is vented
back in to the tank..













Shift THELEVER to reply.

raden wrote:

When you said "remove the plastic nut" .. what did you mean ? With the
head off, there is no plastic nut visible. Instead there's a brass nut
which I can easily turn by hand.

I presume that'll be the one, is the pin located in a hole down the
middle ?

The plumber was here today and yes, the problem was found to be the
thermostatic valve which was stuck about 1/3rd open. Not only was the
pin stuck, the whole valve was seized fast - no amount of wiggling with
pliers or tapping with hammers/spanners was able to shift it. I'm
surprised about how this was able to happen.

As a "stop gap" the plumber has simply removed the valve (so now it just
runs direct) and balanced the return coming from the bottom of the coil
so that the radiators and the water heat "fairly" (as more or less would
have been the case with the thermo valve). I'm going to revisit the
matter in the summer and it's likely we'll stick on a motorized valve
and either a thermostat or a separate timeclock to allow independent
control. I'm likely to go the thermostat route as a few people here
advised same.

Thanks to all the helpful gents who patiently replied here - I've
learned a lot about CH/HW plumbing over the past couple of weeks. A
lot of newsgroups on Usenet seem to be overrun by trolls and morons -
it's pleasing to see some great people here keeping things moving nicely
with their expert advice.

Stuart wrote:

It's a single feed Primatic I have so the cold water going in from

Ah, sorry missed that bit...

--
Cheers,

John.

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