Boiler replacement

grayif

First post! (Asking for help but I intend to stick around and learn/help if I can too).

We're getting out 25 year old boiler replaced in our one bed flat in London. So far we've had 5 quotes, and I can safely say I'm confused.

There seems to be some differing opinions as to whether we need to replace the pipes from the meter to the boiler - there's currently a big drop off in pressure. 2/5 guys say no, 3/5 guys say yes. (Actually one of those 2 guys said we need to just replace the last 2m to give the system a boost.) ???

Anyway the quotes are for:
- get rid of old boiler (all disposal included)
-install new combi boiler (Ideal Logic, Worcester J24i, Vaillant ecotec pro, Glowworm 24 have all been proposed)
- flush system
- replace ~10m of piping from meter to boiler (run it through the flat)
- new flue and condensing pipes
- new valves on our 3 radiators

The quotes are:
British Gas £3800
Company 1 £2800
Company 2 £2550
Company 3 £2400
Company 4 £1650

The 4th guy (£1650) is from Liverpool (we live in London), a contact from my other half's dad. Whilst I appreciate the cost, I can't help but feel slightly uneasy that it's *that* much cheaper. [He's not VAT registered]

Guys 3 and 4 just quoted over the phone; Guy 1 seemed the most thorough and was the only one to check the gas pressure

We have received written quotes from BG, and Guy 1. Guy 2 gave us a written quote but said it might go up by a few hundred pounds when I suggested the pipes might need doing. (I added that on for the above comparison)

Help?

thetrumpetofbelieve

With regards to increasing the gas pipe size, it all depends on what is there at the moment, if it's only a 15mm pipe, it would need to be upgraded to at least 22mm pipe. The reason for this is that new combi boilers require a higher gas pressure to heat the hot water, so that you get "instant" hot water. Also, gas regulations state that when installing an appliance you can only have up to 1mbar working pressure drop between the meter and the appliance, so if you have more that that, then the gas pipe is undersized.

I'm guessing the Worcester Greenstar 24i Junior is the BG quote? But out of all of those boilers that you have listed, they are the best, in my opinion. You can expect to pay more for BG and other large companies as they have much greater overhead costs, but then you usually do get "free" system cover for a year or two.

The person who quoted you with £1650 is probably for the Ideal Logic? Out of the boilers listed, this is probably the worst. Although they do come with a 5 year manufacturers warranty (I believe?), but they would give you some trouble.

Glow worm is now actually owned by Vailliant, and in my opinion, Vailliants quality has gone down recently and are more like Glow Worm boilers (cheaper). But all in all not too bad of boilers.

You should try Scottish & Southern Energy, they usually do a pretty good deal, and offer 0% finance I believe, so not such a big upfront cost of changing the system.

Hope this has helped.

grayif

Hi, thanks for the reply. I want to go with company no. 1. He also is installing a Worcester Bosch. And yes, the pipes are currently 15mm so need to go up.
Fingers crossed for a no-hassle installation. Sets the savings back a bit, but ho hum..

southcoastrgi

24kw is the lowest output combi around & in my view i wouldn't fit one on any property, all combi's will run the rads (if you need more than 24kw on the heating circuit then a combi won't be surficiant for your hot water anyway as you have a big house), it's all about hot water flow rate from your taps, 28kw will give you approx 9 ltr/min while a 38kw will give you approx 16 ltrs/min in the best cases, you will pay more for a higher output boiler but its no good going back to the installer afterwards & saying the hot water performance is !!!!!! & it takes a week to fill a bath, any good installer will run your taps for you so you can see the differences in the boiler outputs before you finally make your mind up. ask for a quote on a "broag" boiler cheaper & better than a worcester IMO.

cosworth_monkey

I take it all the above quotes are including the cost of the boiler?

Don't forget to ask for all of the Gas Safe numbers so you can check online to make sure they are allowed to work on gas.

Again any electrical work will need doing by a qualified electrician.

With regards to the gas pipe size, as a general rule of thumb the supply pipe should be one size larger then the appliance needs. The boiler will be 15mm so a 22mm pipe will be needed (up to the final metre before the appliance) but if you have any other gas appliances (cooker, fire etc) they will need to taken into account. On a normal domestic property 28mm pipe work is more than enough.

Is the boiler a straight swap? Existing is wall mounted or floor mounted? Is it on an outside wall? Will your time clock/programmer need upgrading?

Whilst they are changing the rad valves I'd recommend you change all of the valves to thermostatic ones.

The Worcester is the best of the above. The job should take 2 days.

Hope that helps!