New heating system - boiler choice

[starnberg]

We're refurbing an edwardian semi and need to spec a boiler - builder has suggested a Vaillant 937 which is physically huge.

Based on a three bed one bathroom and cloakroom house I'd guess an 837 would be OK but we're trying to build in maximum flexibility for converting the loft in the next couple of years which will include a further shower room.

Water pressure is OK (2.5 - 3 bar) and flow is around 15l/min. Supply pipe is lead so we'll be replacing that with 25mm MDPE which will (I guess) boost flow but drop pressure slightly (although the comms pipe is also lead and whether Thames Water will sort that is yet to be confirmed).

Have also considered whether an unvented cylinder would be worthwhile to ensure good shower pressures post roof conversion - space considerations would mean this would probably need to go in the loft space. Although siting it would be key so we don't have to move it come conversion time...

Any suggestions/alternatives we should look at? Is an unvented cylinder likely to be viable once we've swapped the supply pipe and can they go in the loft? We've got pretty much total flexibility as the house is currently gutted.

Thanks.

S.

 

[Hugh Jaleak]

My personal preference would be the unvented option. Stored hot water has the benefit of immersion backup should the boiler break down. Friends of mine were very quickly on the phone when their combi packed up, and that was in the middle of summer!

Vaillant are getting poor reports on here at the moment for customer service issues I think, so maybe worth considering before you part with your hard earned.

 

[morrismini]

A new high flow quality combi, not a 937, many are about.
Look at these:

• Rinnai Twinflow: http://www.rinnaiuk.com/Updates-18-09-08/A4 Twin Flow.pdf
• ATAG Q51C 51kW combi with a 13 litre instant cylinder. DHW, 23.2 L/min. Stainless steel heat exchanger. 5 year warranty. ATAG are about the best.
• The Twinflow is a Rinnai and an ATAG in one frame. Rinnai deliver the DHW instantly.
• W-Bosch 550 Highflow (floor mounted) 25 litres/min
• Ethos 54C
• The Remeha Avantaplus 39C combi. Remeha have just bought Baxi, so the Baxi Heat Team will do the servicing soon when they get it all in place.
• W-Bosch 42kW
• There are Glow Worm floor and wall mounted stored water combis - they are two stage DHW delivery. Usually around 13 litres/min when the tank is cool.
• The Alpha CD 50 wall mounted
• Etc
• Etc

Look at the ATAG 51 kW. It can deliver 1392 litres an hour. A cylinder would need to be huge and very expensive to compete with that DHW delivery.

 

[kevplumb]

christ he's off again

 

[Hugh Jaleak]

Unfortunately.... How often have we seen the same info cut and pasted now? OP I would suggest you do a search on other contributions to the forum from morrismini before heeding any of the advice given.

The list price on the Rinnai twinflow is £3,250 before you even think about installation costs.

 

[morrismini]

How often have we seen the same info cut and pasted

No need to re-write when it can be cut & pasted. Did you take notice the first time?

 

[kevplumb]

no need to rewrite anything then

all the crap you post is the same

 

[morrismini]

.

 

[morrismini]

The list price on the Rinnai twinflow is £3,250 before you even think about installation costs.

But it is the best quality and that costs. The ATAG 51 kW is not bad and top quality and approx 24 litres/min. The Avantaplus 39C at 16 litres/min is just under £1K. W-Bosch 550 floor mounted, 25 litres/min, is just under £2K, less than an unvented cylinder with its annual service change, and system boiler for the DHW delivery and all in one box.

.

 

[kevplumb]

bet that sig don't last long drivel

dunno tho sort of suits a giggling fool

 

[morrismini]

.

 

[billy bob]

The list price on the Rinnai twinflow is £3,250 before you even think about installation costs.

But it is the best quality and that costs. The ATAG 51 kW is not bad and top quality and approx 24 litres/min. The Avantaplus 39C at 16 litres/min is just under £1K. W-Bosch 550 floor mounted, 25 litres/min, is just under £2K, less than an unvented cylinder with its annual service change, and system boiler for the DHW delivery and all in one box.

I can assure you ATAG would not let you near their boilers

 

[bengasman]

Nothing beats a properly installed, large unvented cylinder, but, it is significantly more expensive than a large combi.

Vailant is not a bad boiler, but the after sales service is atrocious. I have installed them before, but will now categorically refuse to buy them due to the company's attitude, and I am certainly not the only one. Think twice before you choose a vailant.

You may want to take the advice of morrismini with a few grains of salt, he is not a pro, but a rather annoying troll that has been banned several times when he used other aliases.

Last but not least, builders are not plumbers or heating engineers; choose your own installer unless the builder can come up with somebody whose good credentials are verifiable. Very few good installers are willing to work for builders.

 

[billy bob]

Nothing beats a properly installed, large unvented cylinder, but, it is significantly more expensive than a large combi.

Vailant is not a bad boiler, but the after sales service is atrocious. I have installed them before, but will now categorically refuse to buy them due to the company's attitude, and I am certainly not the only one. Think twice before you choose a vailant.

You may want to take the advice of morrismini with a few grains of salt, he is not a pro, but a rather annoying troll that has been banned several times when he used other aliases.

Last but not least, builders are not plumbers or heating engineers; choose your own installer unless the builder can come up with somebody whose good credentials are verifiable. Very few good installers are willing to work for builders.

I agree, you should seek the plumber & heating installer yourself, all of the new build work I do for the self build market, they employ every trade individually, they get a much better job, as they can select high quality tradesmen specialists in their own field, rather than using a builder who tend to use lower standard tradesmen as they are cheap

 

[kevindgas]

personally i still rate vaillant for reliability, a 600 series with an unvented cylinder would be the best choice look at the Aurostor (twin coil so you can add solar at a later stage) or the standard cylinders from vaillant, megaflow (heatrae) or the santon