Install underfloor heating one room at a time?

[frogs4all]

Hi everyone,

 

We renovating a house we're living in, slowly, one room at a time. Can we install wet underfloor heating in each room as we renovate it?

 

We have a newish combi boiler driving 2 circuits using a diverter valve. The kitchen has underfloor heating with (what sounds like) its own pump. The rest of the house has radiators, most fed by 10mm microbore. The main circulating loops are 15mm and 22mm pipework. During the winter we need a 55 Celsius flow temperature. All the rooms (apart from the kitchen) are timber floors.

 

I'm not sure how to construct a hybrid heating system of underfloor and radiators. Is it feasible to install underfloor heating in a single room we're renovating and connect it back to the main central heating loop? A central manifold doesn't look easy and I'd rather contain the changes within the room being renovated. The longer term plan is to replace all the radiators with underfloor heating, run at a lower flow temperature and, one day, replace the combi boiler with a heat pump. So if each room's UFH needs something to reduce the flow temperature in that room, there needs to be an easy way to switch to whole-house UFH with a lower flow temperature in future.

 

[JohnMo]

You really need to have a manifold to run the UFH and mixer, not run from same circuit as radiators as the flow temp required will be very different.

 

With UFH you need plenty of insulation beneath it, (150mm PIR ideally or more of other insulation materials) otherwise you will spend most of your money heating the ground, not your house. Are planning for this activity?

 

There are good benefits with UFH in a well insulated house, as flow temps can low. In a not well insulated house flow temps can be higher than oversized radiators. If your flowing 55 degrees now, a slight upping of radiator sizing in the main living space is all you need to do for a heat pump. You may be better doing that, make the radiators ok for an ASHP and reap the benefit of low flow temps on your gas boiler and have it setup to weather compensation.

 

Love UFH but it's not right everywhere and every house.

[frogs4all]

Thanks JohnMo.

 

We love the UFH in our kitchen, which is why I'd like the other rooms to have it too. But it is good to challenge my thinking on this - thank you.

 

We only have 2 rooms to do on the ground floor. One is a suspended timber floor, which I'd like to renovate soon. I want to insulate between the joists. Putting in UFH trays and piping at the same time might make sense. The other is suspended timber with a patch of uninsulated concrete where an entrance hall/corridor used to be. I'm not sure what to do with this one but we won't have a chance to do it for quite a while. The upstairs rooms are timber floors. UFH is appealing but they are all carpeted, which I guess might reduce heat transfer from UFH into the rooms?

 

Since we already have radiators in, do you think it would make sense to lay the UFH trays and piping under the floorboards, leave them disconnected, use the existing (or up-rated) radiators for now and switch to UFH when the whole house is ready? We only need the floorboards up in the ground floor rooms (for the insulation) - and one room is far in the future. The only reason I can see for lifting them in upstairs rooms would be to install UFH.

 

[JohnMo]

I really wouldn't bother with UFH in bedrooms ever again. It's a complete waste of time and money. You only need to heat bedrooms for a short period, if at all. UFH unless you blast it with loads of heat (which isn't the idea of UFH) is way to slow to react. So I would keep to radiators. Nice wool carpet and UFH don't make a good partner either, bit like putting a duvet on a radiator.

[frogs4all]

Great advice, thank you JohnMo.

 

I've concluded I'll skip UFH entirely for now. When/if I figure out what to do with the concrete + timber floor room downstairs, I'll reconsider whether to have UFH in that room and retrofit to the other downstairs room, which is next to it.