Underfloor heating tips

Petriix

21.5 degrees sounds uncomfortably hot. 22.5 would have me opening all the windows. 

inkydolphin

QrizB said:

inkydolphin said:

Hi. I just moved into a bungalow with underfloor heating in the kitchen-diner powered by gas combi-boiler. The combi-boiler also runs the radiators (eight including two heated towel rails), one of which (albeit quite small) is in the kitchen-diner.

Congratulations on your new bungaow with gas-fired wet underfloor heating! We often get posts from people with electric underfloor heating and huge energy bills. You shouldn't have that problem.

inkydolphin said:

I was after some advice on general principles to use for a setup like this in terms of settings for the thermostat governing the underfloor heating (it works on air temperature not floor temperature) - i.e. should this be set to a lower temperature than the thermostat in the hall that controls the radiators, what flow-rate temperature to set for the underfloor heating water (presuming it's adjustable) and how long it should be on for and at what time of day to make it worth having.

I'd suggest you set the UFH thermostat to suit your needs in the kitchen-diner, and ignore the radiator in that room (or turn the valve off). Run the rest of the house like a "normal" system.
The UFH water temp is probably set by a blend valve, and might not be user-adjustable.

@QrizB Thanks - sounds like a sensible way to look at it.

inkydolphin

JSHarris said:

Our UFH has the pipes embedded in reinforced concrete, with a mass of about 15 tonnes.  Takes forever and a day to heat up when we first turn the heating on (usually around the beginning of November), but stays warm for a very long time.  We use it as a storage heater, heating it up with the heat pump during the Economy 7 off-peak period, with the floor then releasing heat to the house over a long period.

This works pretty well, but can get caught out if there's a sudden increase in outside temperature, as happened last night.  At 10 o'clock last night the outside temperature was down at 2.5°C and stayed low until the early hours (so the heat pump upped the flow temperature to compensate).  Right now the outside temperature has risen to 9.8°C, so the floor has a bit too much stored heat and the room temperature is about 0.7°C above the thermostat setting of 21.5°C.

We have a similar slight issue with the house getting a bit warmer than it should if we get an unexpectedly sunny day in winter, because there's no way to stop the warm floor from giving out heat (although the heat output does significantly reduce as the room temperature increases - Newton's law of cooling at work).  Not a major issue, we aim for a room temperature of 21.5° and it sometimes gets as high as 22.5°C when something like this happens, so not too high.

@jsharris Thanks. So really a case of seeing how quickly ours heats up and how long to lose the heat and a bit of trial and error to find our sweet spot.

JSHarris

Petriix said:

21.5 degrees sounds uncomfortably hot. 22.5 would have me opening all the windows. 

I guess we're all different, our preference for having the house on the warm side probably comes from many years living in houses that were a nightmare to heat, and which consequently always felt on the cold side somewhere in the house, plus we both feel the cold more as we've got older.  Despite my best endeavours to improve insulation levels and get rid of drafts at our last house it fell into this category.  The biggest culprit was a concrete ground floor with zero insulation.  Only way to avoid cold feet was to lift them off the floor!  We put up with it because we were already planning this house, but it did heavily influence my decision to use UFH here.

MultiFuelBurner

Although the formulas are perhaps helpful in a planning stage most of us don't get to know exactly what has been put under the floors and inspected every section.

We have wet UFH heated by the heat pump on a high B EPC rated house but unfortunately this was a one off build and we are not the first owners so cannot categorically say what the construction is and how the UFH was run on the ground floor.

All we can say is that this is the cheaper house we have run so far and it may just be a feeling but you cannot beat UFH with wooden floors for the warmth you feel on your feet. This really does seem to make a difference as the thermostats may read a bit below where you might think you feel comfortable 

Scientific formulas are all well and good but you cannot beat certain feelings of warmth with UFH in our opinion.

@inkydolphin you just have to find your sweet spot