Which boiler and does the quote seem reasonable?

[gms]

Hi All
I am in the process of finalising a new system for a 3 story semi with 5 bed rooms 2 bathroom 2 kitchen and shower room. Approx 142sqm. The house functions as two houses for us (a couple) and one of my children's family of 2 adults and a child.

We are removing an old baxi boiler and re-sighting the new one in the bathroom wall where its flue can run into a chimney. A new cylinder with solar provision and 2x 20 tube collectors with all the switching and valves and controllers along with the obligatory powerflush and magnaclean inhibitor is proposed. The quote is £8.5k.

I have two questions:
The bolier:
We have opted for a vented system boiler. We have good cold water pressure and the hot water pressure is as we like it.
We were looking at two manufacturers: Viessman 30kw or Worcester Bosch greenstar of a similar output.
We had decided on the Worcester Bosch but then I found that it could not be wall mounted with a flexible chimney flue.
Our contractor then recommended we consider an ATAG A 32kw . There does not seem to much information on the reliability or quality of their boilers .
Do any of you know this manufacturer and have an opinion on there suitability and reliability?

Secondly and I know this is 'relative' but do you think as a ball-park figure the quote of £8.5k is reasonable?

Thanks for your assistance

 

[Agile]

30kW sounds far too high a power to me ! Do you really already have a gas bill over £2500pa ?

It sounds to me like a DIY design by someone without the right experience. Boilers are sized on the whole house heat loss! Does you house really lose 28 kW ?

My ball park quote system would indicate a lower price could be obtained and I would advise you have a seperate quote and probably two different installers for the boiler/cylinder and the solar panels/controller.

As solar has no cost/saving benefit it is seen as a luxury and is overpriced in both supply costs and usually installation.

Tony

 

[gms]

Hi Agile/Tony
Thanks for your reply
Sorry a typo in my house size should have read 410 sqm not 142. This makes a big difference in the boiler size doesn't it?
Your suggestion of a separate installer makes a lot of sense.

Thanks

gms

 

[Agile]

Yes, a floor area three times larger does indicate a much higher heat loss and perhaps 30 kW might well be close to the required boiler power.

Whilst floor area is useful as a quick check to confirm calculations its still the whole house method which should be used to size a new boiler.

I use four methods in each case, owners evaluation of existing boiler power, whole house, existing rad output and floor area as a final check based on 50w/m² for a well insulated house and 100w/m² for a less well insulated house.

The whole house method should be the overiding source taking into account future insulation improvements. For example your house might be 30 kW at present but could be 24 kW if you had cavity wall insulation. So the best solution is a 24 kW boiler and wall insulation.

Tony

 

[gms]

Thanks again Tony,
We have cavity wall insulation and one living unit is mid terrace whilst the other half is a semi. Are you saying that a 24kw boiler working to capacity is working more efficiently than a 32kw not working so hard?
If as you suggest I have someone install the new boiler separate from the solar installation any suggestions for a contractor to install it? We live Ashford side of Canterbury close to the M2.
PM me you have any suggestions [email protected]

Thanks

Garry

 

[kevindgas]

why are you wanting the flue to go in a chimney? is your bathroom big enough for boiler to be outside the zones? what solar panels are you being quoted for and what "controls" are included?

if we were doing this job including a plate heat exchanger for reverse heating we would be charging around £7K

 

[gms]

Thanks for the interest Kevindgas.
Our bathroom is quite small and is the only alternative site for the boiler which does not involve unacceptable disruption and additional pipe work other than a replacement baxi back boiler which has insufficient power. The chimney where the BBU is now runs up through the bathroom and therefore the new wall mounted boiler can legally be flued into it. Its not possible to flue it elsewhere in the bathroom.

The solar installation is as follows:
2x 20 tube TZ58/1800 evacuated tube collectors
Flashing kits for solar pipe-work installation through into loft space
DN16 flexible stainless steel pipe-work from collectors to cylinder location
Flow-Con S solar pump station unit at cylinder location
Solar rated 18L expansion vessel to pump station unit
22mm solar air separator unit on solar return pipe-work
Associated controls, pipe-work and fittings for solar panel installation

Thanks

Garry

 

[Agile]

Chris of Viatec ( spelling ) is in your general area and won an installer of the year award and likes solar as well. He likes Viessmann boilers.

I am sure he would do a good job but may not be the cheapest. Anyone know how to contact him or what his posting name is on here? Why oh why are professionals allowed to use stupid anonymous pseudonyms?

Tony

 

[Gasman77]

Maybe cos most RGI's are here to give advice, and not tout for work? unlike some.......

 

[gms]

Thanks again Agile
Managed to find this chap form Sittingbourne which is quite close to me.
Not spoken to him yet but seems to have a good reputation and as a bonus he seems to specialise in ATAG boilers

Not sure if the forum allows posting these details but they are freely available on the web;
http://www.vietec.com (cant seem to load his page and a quick 'whois' search on TUCOWS which is where his domain registered says it owned by someone else)

Christopher Flaherty

Sittingbourne (KENT)

Clear Skies reg: 2118136

Thanks again

Garry

 

[Agile]

Thats Chris!

It would be better if you edited out his address and telephone number but he is very competent.

He may be able to advise about grants towards solar.

Although some apparently may not agree, I think part of the usefulness of a site like this is that we can sometimes suggest competent people in your local area who can carry out work to a high standard.

Expect him to be good but not necessarily cheap as those qualities dont go together. You usually get what you pay for.

Tony