Underfloor Heating - Wood/Tile

rampantbunny

Was speaking with a guy who built a house about two years ago.
He said if he had to do it again, for those rooms that were in the same UFH zone, he would definitely keep all his floor finishes the same e.g. all tile or all wood.

The problem he would avoid is the time it takes for the timber floors to get up to temp versus the tiled floors. He is constantly exercise experimenting with stats.

Interested to hear any views on this, especially as experts I have spoken with recommend not having any zones for UFH at all.

BarneyMc

When you say timber I assume you mean engineered? Also what thickness? Also did he slab the walls?

I would assume for solid, non-slabbed walls this is not such an issue as the temp should remain fairly constant (or that's what I would hope!).

rampantbunny

Engineered Barney...not sure what thickness but nothing special order. House is of ICF construction, therefore no separate insulated board internally.
Internal separating walls are poured concrete and I don't think they were insulated in the same fashion as the external walls i.e. bare concrete therefore he has thermal mass.
Regardless he obviously lives in a way that requires that his heating system be turned up/down.

Personally, my first thought was that he overdid it on the timber floor underlay, but the guy seems very clued in so I'd be surprised.

stickybookmark

I'm planning on only having 2 zones for my house - upstairs and downstairs. In an open plan house you're better off just having the whole house as 1 zone. This is the best way to run the house efficiently and keep heating bills down. I'm not putting any wooden floors in the house so as to get the most out of the underfloor heating. I am however planning on having some rooms tile and some rooms polished concrete, wonder if the same issue could occur

paulmclaughlin

Wouldn't having fewer zones mean when the floors reach the lower threshold and begin the reheating process there would be a greater drain on the hot water supply?

rampantbunny

paulmclaughlin wrote: »

Wouldn't having fewer zones mean when the floors reach the lower threshold and begin the reheating process there would be a greater drain on the hot water supply?

The way I see it working (I'm not an expert)..
If the floors start to lose their heat, you should still have thermal mass (if you've built with thermal mass in mind). This means your stat will not react to a drop in floor temp. They will react if the area where the thermostat is located is cooler so the heating 'cycle' should not kick in before it's required.
If the thermostat is on the floor, that's another problem.

Raises something I hadn't considered though; in a single zone system, where is the optimum location for the single thermostat.

In the back of my mind, the idea of a single UFH zone still bothers me with respect to the upstairs bedrooms not being regulated differently to downstairs.

BarneyMc

rampantbunny wrote: »

The way I see it working (I'm not an expert)..
If the floors start to lose their heat, you should still have thermal mass (if you've built with thermal mass in mind). This means your stat will not react to a drop in floor temp. They will react if the area where the thermostat is located is cooler so the heating 'cycle' should not kick in before it's required.
If the thermostat is on the floor, that's another problem.

Exactly my thoughts. The floor is merely releasing the heat. It's then up to the thermal mass in your walls and slab to soak up the heat and realease it back into the rooms slowly. Am I right in saying then that a floor that gives up its heat quickly is less dependent on insulation?

rampantbunny wrote: »

Raises something I hadn't considered though; in a single zone system, where is the optimum location for the single thermostat.

Probably away from other heat (or cool) sources or like stoves, cookers, windows etc? Maybe the main living room?

rampantbunny wrote: »

In the back of my mind, the idea of a single UFH zone still bothers me with respect to the upstairs bedrooms not being regulated differently to downstairs.

I think it's one zone PER FLOOR that was suggested which makes perfect sense.

rampantbunny

BarneyMc wrote: »

Exactly my thoughts. The floor is merely releasing the heat. It's then up to the thermal mass in your walls and slab to soak up the heat and realease it back into the rooms slowly. Am I right in saying then that a floor that gives up its heat quickly is less dependent on insulation?

You'd still want your floor to give up it's heat in the right direction. Heat rises etc. but it will be robbed of heat from the colder layer underneath if no insulation.

BarneyMc wrote: »

Probably away from other heat (or cool) sources or like stoves, cookers, windows etc? Maybe the main living room?

People generate heat. If your living area is off your kitchen and open plan is the nature of your build, then I'd say your living area will be warmer than other rooms on the same floor. If it is, your thermostat will react to the temps in that room, keeping other rooms in that zone cooler. But then to complicate things you have the balancing effect of MHRV...where is the head spinning Smiley when you need it.

BarneyMc wrote: »

I think it's one zone PER FLOOR that was suggested which makes perfect sense.

My build will be a single zone. I posted on here last year querying whether single zone or multiple zones were the way to go. Most recommended a single zone for whole house, not one per floor. The installer reckons zoning reduces system efficiency and posters maintain MHRV will balance the temps anyway.

The common messages I see coming through are:
'thermal mass = slow response = steady temps = less system stress/more efficiency = lower bills'
'single zone = less stats = less heating cycles = less system stress/more efficiency = lower bills'

The slow response conundrum; as per above, desirable. But in Ireland our temps can swing from day to day. If you want a rapid injection of heat, you don't really have that option unless you have a secondary source such as the gas fire in the corner that was bought as an ornament (or an inline MHRV duct heater). In summer, well you can just open the windows. The efficiency of the MHRV in this scenario is not important as you're not concerned about it doing it's heat exchanger thing, only bypass.

BarneyMc

rampantbunny wrote: »

You'd still want your floor to give up it's heat in the right direction. Heat rises etc. but it will be robbed of heat from the colder layer underneath if no insulation.

Oh, it still needs insulation but maybe just not as much.

rampantbunny wrote: »

The slow response conundrum; as per above, desirable. But in Ireland our temps can swing from day to day. If you want a rapid injection of heat, you don't really have that option unless you have a secondary source such as the gas fire in the corner that was bought as an ornament (or an inline MHRV duct heater).

Yes and to throw another spanner into the mix I hope to use my wood burning stove extensively but then again some days I won't light it. I'm hoping that the HP controls will be able to deal with this and not overheat the house. I'm guessing a quick response (liquid screed) approach would work best here?

Anyway I'm happy I'm going down the thermal mass route as it seems to make perfect sense for the passive/near passive house.

Calahonda52

rampantbunny wrote: »

'single zone = less stats = less heating cycles = less system stress/more efficiency = lower bills'

I dont understand this. Just teasing out the issues here.

Is the suggestion that for conventional heating systems,
such as gas,oil etc that we multi zone: water, up stairs, down stairs, etc.
but if we go UFH that its just water and the rest.


Would the buffer tank not reduce the cycling on the heat source?

What I would say is that the more piping that is laid, the greater the distribution area and therefore the lower temperature that the system can run at, which is why in Europe they are heading towards capillary mats.
The link is just for the idea, not a recommendation
http://www.clina.de/Funktion/Wirkungsprinzipien.php

There is an english tab

rampantbunny

Calahonda52 wrote: »

I dont understand this. Just teasing out the issues here.

Is the suggestion that for conventional heating systems,
such as gas,oil etc that we multi zone: water, up stairs, down stairs, etc.
but if we go UFH that its just water and the rest.


Would the buffer tank not reduce the cycling on the heat source?

What I would say is that the more piping that is laid, the greater the distribution area and therefore the lower temperature that the system can run at, which is why in Europe they are heading towards capillary mats.
The link is just for the idea, not a recommendation
http://www.clina.de/Funktion/Wirkungsprinzipien.php

There is an english tab

I used the word 'cycles' and it's probably the wrong term because that's more than likely to make people think of their heat pump ramping up to inject more heat into the system.
I'd think of it in terms of a steadier temp meaning less circulation of hot water from buffer to UFH circuits even. The more times you have to circulate the more heat you lose, bit by bit, as the hot water travels...in turn placing a demand back on the HP sooner to 'cycle' and heat more water.

I don't really have any comment to add to the traditional methods of heating and zones for those systems. Put another way, I haven't a clue...mightn't have a clue about the HP + UFH situation either but I'm happy with my illusions for now.

We're going way off topic anyway at this point.