On Wed, 21 Dec 2005 15:07:14 +0000, danw wrote:

I'm seeking advice.

We're currently looking to replace our system boiler and hot water tank.
The boiler and tank are too small for our house (detached, 30s, 3 beds,
one bath, 3 downstairs rooms with small kitchen extension).

We've had a couple of heating engineers in and are receiving conflicting
advice; as I am sure I will get here!

First chap said that a combi would be no good for our house. He said he
would never use them and that they are no good for a house of our size.
He also said that we would need to replace our old iron gas supply, even
though it appears to be large enough.

Second man said that a combi would be fine, he recommended a
floor-standing, Worcester Greenflow. Said we wouldn't need to replace
the gas supply it would be fine. Said a wall mounted boiler would not be
big enough. Having a floor standing boiler is less than ideal as it
would take up much needed floor space in our small kitchen.

Third man says we would be fine with a wall mounted combi but said we'd
need a new gas supply as old iron pipes a likely to rust and this can
get inside the boiler. He also said they are prone to cracking and leaking.

What we would ideally like is: a combi, wall-mounted, with no new gas
supply if possible. We are a small family (2 little kids), with not a
lot of spare cash, and not a lot of room in our kitchen for the boiler.

I know that, ultimately, the decision is ours but if anyone has any
advice for us it would be much appreciated.

For a wall hung combi you have to ask yourself if you are going to be
happy with around 10 litres/minute of HW flow. You may well be or you may
well not be, the matter is one of taste and _must_ be answered before the
rest of the questions.

I would expect that for your house around 15-20kW will be
sufficient, what is the power of the current boiler? Did it ever heat the
house?

A 'standard' (900-450mm) replacement unvented cylinder complying to
current regs should provided enough HW for a bath every 20mins.

IME it is often not the capacity of the cylinder that is the problem but
the reheat time.

If the gas pipe work is not rusting and adequate size it can be reused.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html