boiler questions

[suiko]

I'm having an Ecomax (heating only, keeping old hot water tank) put into my smallish three bed terrace house in Oxford, and just wanted to check a few things after getting conflicting info from two installers.

The one my installer is choosing is an 18kw one - is this too big? The other guy says I should have a 13kw one, but the first one says the

18kw is fine, and can be set at the kilowattage you choose. Obviously I'd like the system to run as efficiently as possible as it is certainly not cheap! Any tips related to this? Also, the first guy is intending to remove the make up tank from the loft, and the second says this isn't necessary if I have the 18kw boiler.

Thanks for any help!

[Ed Sirett]

It is very probable that the 13kW unit would be sufficient for a small terraced house. It depends on the insulation and draught proofing. However the penalty for getting a boiler under sized (a cold house in cold weather) is much bigger than for slightly over sizing (slight increased gas bills). I suspect the 13kW comes from either experience or calculation or both. The 18kW may come from the existing boiler?

For a general discussion of Sealed systems see FAQ. This is not a matter that is dependant on the power of the boiler.

In order to comply with the current energy regs (part L building regs) the HW cylinder will probably have to be replaced.

[Stephen]

Hello,

I have a gas combi boiler: a glowworm compact 100e. It was there when I moved in, about 9 years ago. I don't know how long it was there before that.

About four years ago, water was "leaking" through the overflow to outside. The plumber diagnosed this as a failed pressure release valve. Also, the pressure gauge on the front (what would that be: the pressure in the central heating circuit?) was not reading the correct pressure, so both were changed.

I think the plumber may have said that the expansion vessel might need changing and that if it did, it could be an expensive job, but luckily it turned out to be ok and was left alone.

A couple more years later, I had to have a valve replaced because it would not heat the hot water. Would this have been a three port valve as found in central heating systems?

I have had the boiler serviced ready for the winter (by a different plumber this time) and the plumber says he thinks the expansion vessel is on the way out and needs replacing before the winter.

He says that the difficulty with expansion vessels is that they can be hidden at the back of boilers so the job becomes expensive if they have to dismantle everything else to get to it. He is going to have another look to see how accessible mine is. He has suggested that if it could be an awkward job, it might be easier to fit a new vessel external to the boiler.

My first question is: how good are glowworm combi boilers, particularly this model?

Are the faults I have had over that timescale average or have I been particularly unlucky or even particularly lucky?

What do you think is a ballpark figure for an expansion vessel replacement (and what is it and what does it do)?

Is having a new vessel away from the boiler a money saving idea or is it seen as a cheap bodge?

I have been told that the average life of a boiler is 10-15 years. Does this sound about right? If the new vessel is a very expensive job, would I be better getting a new boiler? What makes and models are good (and which ones are bad)?

Thank you very much. Stephen.

[newshound]

External vessel is a relatively quick and cheap fix, especially if there is a convenient space.

[geoff]

In message , Stephen writes

Yes - easiest solution

No worse than most others

Just type "expansion vessel" into google

It's a valid fix

I have seen various predictions for life expectancy of a new boiler -

5-7 years

[<me9]

I'm happy with my 17YO glowworm system boiler. May replace it in a couple of years depending on future reliability.

doesn't seem too excessive.

I fitted an external one to mine. Parts were not more than £40.

The makers one will cost double, and probably double again to fit. As long as it's not leaking (or is isolated if it is) the external one is a no brainer replacement as lomg as there is room for it.

Probably near end life for that class of boiler. If it's not costing too much in repairs there's little point in replacement IMO.

I'd expect a new (seperate) one fitted for about £80, a lot less than a new boiler (£1500+)

I'll probably go for Worcester Bosch, but Vaillant or Veissman are possibilities.

[geoff]

Oh do f*ck off harry

most boilers have the expansion vessel at the rear, meaning that you have to remove the boiler to get at it

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