Combi Boiler or Not?


Postby billobach181 » Tue Jan 22, 2008 11:43 am

I plan to replace my old open vent Central Heating/HW system boiler. My question is - Will a Combi Boiler be suitable for a 3 bed House with normally only my Wife and Me and the occasional 5/6 people when the family comes to stay? There are those who say you can't beat a hot water cylinder!.
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Postby htg engineer » Tue Jan 22, 2008 8:40 pm

There is no reason why a combi boiler would not meet the needs of your family. You will however need to get a heating engineer out to measure up for the new boiler. He will take into consideration the number and size of the radiators, the number of bath's and mixer showers if any.

For an average sized house with one/two bathrooms a 28KW boiler should do the trick.

If you use electric showers more than you use a bath, then you are heating a whole cylinder full of hot water for washing and washing dishes. So a combi boiler would be more efficient.

As I say, get a heating engineer out to give you a price and he will advise on what boilers are suitable for your needs.

Hope this helps.
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Postby ericmark » Tue Jan 22, 2008 8:45 pm

The Combi boiler saves room, can be more efficient this depends on lagging on cylinder eliminates external control and shower (one) can run direct with medium pressure. It takes longer to fill a bath, and can’t supply multi-showers at same time you can’t fit a power shower. Plus in your case you need to alter the plumbing.
Both Combi and conventional boilers now have a range so instead of switching on and off there output matches demand which works better with TRV’s and most are condensing so a lot more efficient. Many people assume this is only the case with Combi boilers but this is not the case. Having external pumps and valves can cause problems were incorrectly wired or set up especially with the anti-cycle functions.
Many Combi boilers have it all built in including anti-cycle the latter on a Combi only works on the central heating and is basically a timer which stops the central heating re-starting once the boiler has switched of after going below the minimum output until a set time has elapsed. This means not room thermostats are required the TRV’s do all the work. Although this can be fitted to non Combi boilers it is not common and a thermostat is normally required to switch the central heating off once all rooms are warm. So small houses better with Combi but larger houses better with non Combi not necessary open vented the closed system can’t leak as much water if leak happens and central heating water can be hotter although that would also require enclosed radiators. I hope that helps?
ericmark

Postby billobach181 » Wed Jan 23, 2008 12:44 am

Many thanks for your inputs.
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