Linking two boilers and installing a diverter valve.

[dbuk10]

Help please! Our boiler has recently given up on us and is beyond economic; repair, so we are told by the manufacturer!

At the moment we have 2 Vokera boilers (one being a floor standing one and which is the faulty one). Initially we wanted to take both boilers out and install a heat only boiler with a system tank. This type of system was recommended to us by a couple of different heating engineers. However space limitations mean we can't install a tank anywhere apart from changing rooms about and its a lot more expensive.

We are now left with replacing the faulty floor standing one with a Worcestor Highflow 450 or 550, still not sure which. Our house is a 3 bed with two bathrooms. At the moment there are two of us living here but in the future they're could be more of us i.e. kids. The current setup is:

Floor standing boiler - powers most of the rads and bathroom one

Wall mounted - powers bathroom 2, radiators in bedroom 2 and 3 and kitchen hot water tap.

The wall mounted boiler is noisy (its located in bedroom 2) and takes up space but we could probably cut down on the noise by buying a new one, ours is about 8 years old.

My questions are:

can the boilers be linked i.e. to to be able to turn the noisy boiler off when guests are staying and in the event of one failing?

We would like to have the towel rails in the bathrooms coming on independently to dry towels, should we install a divertor valve to do this and does this save heating costs, heating only the two towel rails?

 

[dcawkwell]

Very strange that you have a 3 bedroom house yet 2! boilers.
Unless it is a huge house with only 3 bedrooms.

I would suggest ideally a system boiler with unvented cylinder.

Another option is to install a high flow wall mounted boiler like
a glowworm ultracom store. This has two small internal inbuilt
tanks that can provide very high flow rates to handle
peaks of demand.

The worcester highflow floor standing boiler is also an option.

There is no need to have two boilers for a house your size.

 

[Hufty]

Do you need two boilers? A WoBo 550 has a central heating output of 30kW, which will do 10-15 big radiators at full pelt.

IMO if you're looking at a Highflow and space is not an issue you might be better off getting a system boiler (can go bigger than 30kW if necessary) and a separate unvented cylinder, for about the same money.

You could zone the two halves of the house easily if you wanted to, although if you wanted the most efficient controls for your boiler (eg weather compensation) you might find that they don't handle multiple heating zones so well, which may or may not wipe out the efficiency savings of zoning. A good rule of thumb: zoning is a pain in a domestic settting.

IMO a heat only boiler with a header tank is yesterday's technology in a domestic setting - go pressurised if possible (combi or system).

The towel rails could be zoned separately depending on the pipework. An alternative could be electric elements up 'em on timeswitches, which gives you dual fuel options. When you're only running a boiler to heat two towel rails (1.5kW load say) it's not running efficiently at all so electric might even be better in the summer.

[edit: blimey did it take me over 22 minutes to write all that? dcawkwell's post wasn't there when I started!]

 

[doitall]

A decent Intergas or Atmos heat only boiler, and a high flow water heater.

Assuming the mains can deliver.

 

[dbuk10]

Thanks for the help guys.

The house itself upstairs is not particularly big but the downstairs footprint of the house due to a single storey extension is quite big. Would've liked to go for a pressurised cylinder tank but we just don't have the space.

Do you think there is much point going for the bigger 550 boiler or save £400 and go for the smaller 440? Think we would get a better flow rate on the bigger boiler.

Also do you think it is worth linking the two combo boilers to allow the smaller one to be turned off when water demand isn't that high?