# Is my boiler sufficient for my 15 rads

#### kareni

We have a Grant Vortex Condensing Combi 26 boiler is this sufficient for heating 15 rads and heating water for 3 bathrooms?

We have a Grant Vortex Condensing Combi 26 boiler is this sufficient for heating 15 rads and heating water for 3 bathrooms?
More than likely. It's a combi boiler, so it needs all 26Kw to heat the water used by the bath, shower etc.

The requirement for central heating is usually much less than this - you can check this by using the Whole House Boiler Size Calculator. Set the Domestic Hot Water Allowance to zero as you have a combi boiler.

If you want to find out how much heat your rads give off, use the Stelrad Elite Catalogue

Don't forget that a combi boiler can either heat the house or heat the water; it can't do both at the same time.

sorry slightly confused your saying it is more than likely it is sufficient but then you say it can't heat water and rads at the same time.

No combis heat the heating at the same time as hot water.
If you have the heating on and then run a bath, all the time the bath is running the heating will be off. Its only running hot water for 10 mininutes or so and the radiators will barely cool down in that time and you dont actually notice the heating not working when hot water is running.
Hope that makes sense

Yes although I would think it will struggle with supplying 3 bathrooms
at the same time. If you imagine a morning routine with 6 people
all going into the bathroom running baths and showers between 7 and 8 am.
Will mean the heating remains off for quite a bit of that time.

If you find it struggling with the hot water supply you can add a cylinder heated by the combi to supply a bathroom or two.

You won't be supplying 3 baths at the same time, unless you run them an hour or two before you need them.

sorry slightly confused your saying it is more than likely it is sufficient but then you say it can't heat water and rads at the same time.
I missed the bit about three bathrooms; my reply really applies to the central heating side.

A 26kW boiler will struggle to supply water to three baths or showers at the same time. This is because it will only be able to provide a total flow rate of about 11 litres a minute. A single shower will take a t least 10 litres/min.

Did you have the boiler installed? If so, who specified the size and did they measure the cold water flow rate before saying that a combi would be suitable?

Not quite that bad Dave, it does have a 32Ltr store so can knock out around 15 ltrs/min at 50c

meant to say have they installed a larger expansion vessel, the one with the boiler is unlikely to be anywhere near large enough for a 15 rad system.

A storage combi can only supply an enhanced flow rate for a very limited time, usually about 10 minutes and then it reverts to the basic combi flow rate of about 10 litres oper minute in this case.

Tony

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