Confused about boilers!

[Mike Hibbert]

Hello all,

A mate of mine's boiler has developed a leak. It is leaking from the heat exchanger and is coming out fairly fast(ish). The boiler has got 4 pipes coming out of it, but we are sure that it is not a combi. I'm a bit comfused about the 4 pipes, I was under the impression he should only have 2 (feed and return), so has anyone got any ideas what this is? I have had a look online, but couldn't see a replacement like this. Also, they have has a quote for fitting a new boiler (is a heat exchanger something you can replace? or is this not a starter?) rated at 75000 btu's (not sure what make) for £1200, is this reasonable for swapping a boiler over? (I know it's hard to say without seeing it, but is this in the ball park?)

Cheers in advance.....

Mike

[Roger Mills]

Many older boilers had 4 connections - to facilitate separate hot water and heating circuits - usually with gravity circulation for the HW and pumped circulation for the CH.

Is this what your mate has got? If HW uses gravity circulation, one pair of pipes is likely to be 28mm, compared with 22mm for the CH (or the imperial equivalent of 1" compared with 3/4").

Roger

[Mike Hibbert]

Thanks Roger, this sounds about right, he says that 2 pipes are bigger. How would you go about replacing this? Can you replace like with like or can you not get these anymore?

Mike

[Bob Minchin]

My Thorn M series boiler is like the one Roger describes. Rubber gaskets are used to seal the chest and block where the pipes connect. They fail every now and then and need replacement. It must be quite ancient having been converted from town gas to natural gas well before we moved in and we have been here 21 years. My local gas spares supplier stocks the gaskets.

You could find a simple low cost repair is all that is needed.

Bob

[IMM]

Make of boiler? Is it cast iron? Does it have a cylinder? Etc.etc??

[Mike Hibbert]

Errr, dunno, dunno, and dunno!

Bearing in mind, that my mates idea of wiring in an outside light would be to put a plug on it and run it through the window when needed, I haven't been able to get much info out of him! I will post back when I have been round there!

Cheers Mike

[Roger Mills]

I'm not sure how many (if any) modern boilers have 2 pairs of connections. I suppose you can still run two 2 circuits off one pair as long as you split them *very* close to the boiler - and avoid any nasty bends on the gravity circuit.

If you do keep a gravity cicuit, you should at least put a zone valve in it to convert it to a C-plan system (see

)

That way you can have independent control over the HW and CH.

Better still to convert it to fully pumped if you can (see S-plan or Y-plan in the above reference).

Roger

[Mike Hibbert]

Right, it is a GlowWorm SpaceSaver (?) 75.

Does this help at all? I have found a website that sells parts and they have a heat exchanger for £530 which seems a bit steep considering the age of the boiler and its likelyhood to pack up again.

[IMM]

Get rid. old, inefficient, expensive to run, etc. go condensing. Ideal Icos or Isar. The Isar is a combi, so it can heat the cylinder and the shower run through the water section giving a power shower.

[Andy Hall]

I had one of those until just over a year ago. It wasn't bad in its time but not very efficient at about 65% SEDBUK rating.

Items started failing - first thermcouple (cheap), then thermostat (expensive for what it was). I had planned to exchange it anyway and did so before anything else went.

I certainly wouldn't spend anything like £500 on a boiler of this age and type. This is most of the way towards a nice new condensing boiler like a Keston Celsius or an Ideal Icos.

Since I replaced mine with a condensing model, gas consumption has reduced by 25-30% of previous amounts, so depending on use, the payback can be quite short even though the condensing products cost slightly more than non-condensing. These have SEDBUK efficiencies of around 90%.

.andy

To email, substitute .nospam with .gl