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Andrew Smith
Andrew Smith, HVAC Technician
Category: HVAC
Satisfied Customers: 3629
Experience:  Heating and Controls engineer
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I have just built an extension on my house, its going to be

Customer Question

I have just built an extension on my house, its going to be a games room and I fancied putting in underfloor heating on a separate zone.
the rest of my hose has normal radiators that come on at 6.30 am -9.00 am then again 4.30-10.30pm.
I am told that the underfloor heating must be left on as it takes a while to warm up .
My house is quite a large house so we have to run a 45kw keston Boiler , so the question is would it be uneconomical to run this boiler all day just for the sake of one room (7.0mx 6.0m),or should I just stick to radiators?
Submitted: 3 years ago.
Category: HVAC
Expert:  Andrew Smith replied 3 years ago.

Andrew Smith :

It does not take all day to heat up

Andrew Smith :

Perhaps with a low kW electric system.

Andrew Smith :

This would work if you can tee into the heating before anything else - the first tee off at the boiler?

JACUSTOMER-qvbevjby- :

Andrew

Andrew Smith :

Hi

JACUSTOMER-qvbevjby- :

andrew, the system i am talking about is a water fed system with its own zone as i stated originally , the question was will it be economical to run along side a standard sustem ?

Andrew Smith :

I understand

Andrew Smith :

If you can tee in right at the boiler then you can use a 2 port valve on the new circuit

Andrew Smith :

Plus a 2 port on the existing heating

Andrew Smith :

wire it as an S plan

Andrew Smith :

so when you want your underfloor on only then it will only be that circuit running

Andrew Smith :

you will just need a room stat in the area to control the valve

Andrew Smith :

The boiler is then run by the two valve independantly

Andrew Smith :

The room stat reaches temperature, the valve shuts and the boiler turns off

Andrew Smith :

Quite economical

Andrew Smith :

You will have to fit a mixing valve at the underfloor end though as standard heating temperatures will be too hot for the floor or if you run at underfloor temperatures then you heating may not heat the house effectively

Andrew Smith :

Sorry - typing as fast as I am thinking, do you understand this?

JACUSTOMER-qvbevjby- :

i Do Andrew, the underfloor has its own feed and zone so its totally seperate from the other system, i was just worried that it would be expensive to run withit just being for 1 groundfloor room, as i was told you need to keep underfloor switched on and just let it use the thermostat , because the water takes a while to warm up< is that so?

Andrew Smith :

You may be only running it as 45 degrees, but will be fed with 70 water from the boiler and then mixed down to 45 degrees

Andrew Smith :

The boiler will run for an hour but then turn off and then turn on again when the return temperature drops again

Andrew Smith :

Just like having a large cool radiator under the floor

Andrew Smith :

The room stat will control this and can be set to a minimum air temperature of 15 degrees or so

Andrew Smith :

If you wanted to run radiators then it could be controlled exactly the same but would heat up quicker due to a higher water temperature

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