What are your UFH temps

C

Charlie 07

Registered User
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Recently moved in to house with UFH and still trying to get that 'comfortable' feel that everybody talks about with UFH. Have been running it at 18 C from 645-810 every morn and at 18 C from 6-10pm. We are out during the day and wonder if we are using it efficiently? from reading in AAM some people seem to set it at 20 C 24x7 and others set it as you would with rads. So how do u programme your UFH?
(Recently got 500l gas fill so will be watching this like a halk!!)
Thanks
 
mine is 21 degrees which is moderate - ie comfortable for men and children but a woman might need a jumper.

keep it on 24/7 the way God intended.

I'm discovering these boards are full of skinflints who install expensive systems and then sit freezing in the cold.
Cannot understand it.
 
sfag said:
mine is 21 degrees which is moderate - ie comfortable for men and children but a woman might need a jumper.

keep it on 24/7 the way God intended.

I'm discovering these boards are full of skinflints who install expensive systems and then sit freezing in the cold.
Cannot understand it.
Click to expand...


sfag,
for UFH to be working 'correctly' and at best efficiency....
it should heat up a thermal mass slab at night time and this slab is supposed to release the heat during the day. there maybe days in winter you do require it on at longer times, but if you have it on 24/7 all year round id seriously quesion
1. how its set up
2. if the construction of the house is suitable
3. how much degree of control you have with it
 
I have UFH and I turn mine on 3-4 hours per day from about 4 PM onwards. My tiles are still warm in the morning afterwards. I have an oil condensing boiler running mine!
 
18C on the stats running for about 6 hours a day, the house is a new build & very comfortable
 
I find that the more I look into central heating systems the more questions I have. I built a few years ago and went with a wood pellet boiler, rads and an open fire with back boiler. If I had my time over I would probably change a few things but I still would not be confident of making the right choices.

How is UFH supposed to be used in order to get the best from it?
With that in mind, what is the best system (in terms of efficiency) to heat the water for UFH and why?
Does your UFH temp depend on how you use it?
Does your house need to be constructed in particular way in order to get the best out of UFH?


Thanks,
Pat
 
Currently running at 19.5C. Comes on for 1.5hrs in morning and 1 hr in the evening. Most evenings we light a small fire in the stove in the sitting room too. Temp drops to about 18 - 18.5 overnight but still Ok for sleeping. Plan to run it constant off the stats for a month trial over Christmas once I've fitted and oil level monitor to the tank.
 
If your UFH is set up properly you should be able to have your room stats set at a comfortable temp say 18c for bedrooms and 21 for living roms. This way if your room calls for heat it should open a valve on your UFH manifold start the mixing pump and start your boiler, heatpump or whatever heat source you have running the system. Everything should be automatic.
 
I have a similar query - we run UFH from a combination of solar and gas. Gas has become very costly with fills now costing c. 1k euro, and in cold weather (Dec - Mar) a tank only lasts 6 weeks. We had been advised to run it constantly via zones which are thermostatically controlled (c. living rooms 19/20c/bedrooms 15/17c). This we were told was the most efficient way to run UFH. But with fuel costs so high I am considering using the timer to knock it off at night and come back on a couple of hours before we get up in the morning.

Any expert advice? (house is single storey 2.5k sq ft, well insulated).
 
i have 2000 sq foot house too. underfloor heating with oil boiler.
house is very well insulated but not airtight. house is built in a windy spot.
house has 9 underfloor stats. when a stat looks for heat boiler comes on.
last year i ran the system 24/7 and used buckets of oil.
what was happeningwas stat1 would look for heat and boiler would come on. when stat 1 went off, stat 3 might come on. when stat 3 went off stat 8 might come on etc etc... theis would fire the boiler and was going through tank of oil every 6 weeks.
now i set clock for underfloor heatnig to come on from 7-8, 2-3, and 5-7.
living area at 21 degreesC, hall/bathroom at 19degreesC, bedroom at 18degreesC.
house is always warm and very comfortable.
i also have 300 litre hot water tank, dual coil onto the boiler, heat water for 1 hour/day from 5-6 in the morning and have hot water till next day.
 
The problem with most oil boilers running UFH is the temperature they run at. Most oil boilers are mild steel and have to run at 60c. UFH needs only a low temperature so you are heating water in excess all the time.
 
magtape said:
The problem with most oil boilers running UFH is the temperature they run at. Most oil boilers are mild steel and have to run at 60c. UFH needs only a low temperature so you are heating water in excess all the time.
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magtape...

is it correct to say that oil and gas boilers running UFH actually have to be mixed with cold water to reduce temps before entering the UFH system?...
 
sydthebeat said:
sfag,
for UFH to be working 'correctly' and at best efficiency....
it should heat up a thermal mass slab at night time and this slab is supposed to release the heat during the day. there maybe days in winter you do require it on at longer times, but if you have it on 24/7 all year round id seriously quesion
1. how its set up
2. if the construction of the house is suitable
3. how much degree of control you have with it
Click to expand...

I'm pretty sure these systems have nothing to do with low rate night time tarrifs. The floor should heat when the room thermostat calls for the heat at what ever time that is.
My floor (4 inches of concrete) will cool down 2 hrs after switching off. How is that gonna last all day till the following night?
 
sydthebeat
Yes thats correct, the flow to the UFH manifold mixes with the colder return from the floor to give a set temperature.
 
sfag
The problem with most UFH is the depth of concrte over the pipes.
50mm to 75mm is enough over pipes as this is easier to heat and to control.
Too much concrete means longer to heat and more cost to do so.
 
Seems like some folks have their thermostats in the floor from reading the above - I thought they had to be in the room on the wall?

FWIW. More and more I've come across ufh systems that havent been wired correctly and as result people think they aint working correctly. The wiring is cruical.
Mine was wired incorrectly and it constantly ran heating and cooling the water evey alternative minute - A disaster.
A friends was wired incorrectly and his wood pellet boiler generated the heat, sent it round in a loop, skipped the rooms, and never fired down.

With a gas boiler the boiler will keep the room tepid by using a trickle of gas when its warm as opposed to a gigantic blast used to fire up when the house is cold. With my correctly wired boiler keeping it on 24/7 cost no more than running it on radiator style timings.

I even moniter the effect of switching the heatin off for a long weekend and then reheating the house on the evening that I returned. I compared this with leaving it on for a full weekend. The cost was the same. My boiler is a gas glowwarm.


I'd say observe your systems and count the meter units and take other opinions.

UFH systems generate a max of 45 degrees of heat to the floor and that will be cooled down before the water completes its heat. Once switched off surely there is no way the floor can continue to heat your house all day?.
 
sfag said:
Seems like some folks have their thermostats in the floor from reading the above - I thought they had to be in the room on the wall?

FWIW. More and more I've come across ufh systems that havent been wired correctly and as result people think they aint working correctly. The wiring is cruical.
Mine was wired incorrectly and it constantly ran heating and cooling the water evey alternative minute - A disaster.
A friends was wired incorrectly and his wood pellet boiler generated the heat, sent it round in a loop, skipped the rooms, and never fired down.

With a gas boiler the boiler will keep the room tepid by using a trickle of gas when its warm as opposed to a gigantic blast used to fire up when the house is cold. With my correctly wired boiler keeping it on 24/7 cost no more than running it on radiator style timings.

I even moniter the effect of switching the heatin off for a long weekend and then reheating the house on the evening that I returned. I compared this with leaving it on for a full weekend. The cost was the same. My boiler is a gas glowwarm.


I'd say observe your systems and count the meter units and take other opinions.

UFH systems generate a max of 45 degrees of heat to the floor and that will be cooled down before the water completes its heat. Once switched off surely there is no way the floor can continue to heat your house all day?.
Click to expand...

sfag...
theres a fundemental difference between the way a radiators central heating system works compared to an underfloor heeating system.

In a rad system the heat in the hot water in the pipes is quickly dispearsed into the air, as the steel rads dont hold the heat at all.... this system is very responsive to changes in the temperature in the pipes.. ie heat up quickly, cool down quickly. This syetm typically runs at about 60-70 degreees.

in an UFH system the heat in the pipes is NOT dispearsed quickly into the air, its held or 'stored' in the concrete screed. this system typically runs at 35-45 degrees. This concrete screed then uniformly releases the heat slowly into the room throughout the day. This is why the system is essentially dependant on construction. You say your slab cools after 2 hours, id be seriously worried about your construction. You possibly have too little insulation in the floor construction or large thermal bridges throughout your floor.
Its very interesting to note that, under the old regs (2002 + 2005) the required u value for a floor with UFH was 0.25.. typically similar to a wall u value. However under the new 2007 regs you must construct a floor with a u value of a minimum of 0.15 when using UFH. This means UFH floors have to be insulated to a greater degree than most roofs!!!!!
 
sydthebeat said:
sfag...

This concrete screed then uniformly releases the heat slowly into the room throughout the day. This is why the system is essentially dependant on construction. You say your slab cools after 2 hours, id be seriously worried about your construction.

This means UFH floors have to be insulated to a greater degree than most roofs!!!!!
Click to expand...

I cannot feasabily see how 4 to 6 inches of floor slab dept can emit heat all day. Theres nothing magic about that stuff. Its just sand and cement (I'm excluding easy screed here). My floor insulation was regulation standard which I believe was 60 mil hd (kingspan). Again that stuff does not work miracles. But if you say it works that way for you I suppose I have to suspend my disbelief.
It doesent get completely cold within two hours but it stops emiting sufficient heat.

As a matter of interest my gas bill last year was 2600 (hob and water included but they would amount to about 400) .
The house is 4000 sq ft excluding an unheated garage.
One side of the house is all glass and one room is 20ft tall.

I adhered to regulation on the insulation and oversaw the build myself.
The glass has gas and e-coatings.

Do you reckon I'm doing well on the bill or poorly - I appreciate the comments
 
sfag said:
I cannot feasabily see how 4 to 6 inches of floor slab dept can emit heat all day. Theres nothing magic about that stuff. Its just sand and cement (I'm excluding easy screed here). My floor insulation was regulation standard which I believe was 60 mil hd (kingspan). Again that stuff does not work miracles. But if you say it works that way for you I suppose I have to suspend my disbelief.
It doesent get completely cold within two hours but it stops emiting sufficient heat.

As a matter of interest my gas bill last year was 2600 (hob and water included but they would amount to about 400) .
The house is 4000 sq ft excluding an unheated garage.
One side of the house is all glass and one room is 20ft tall.

I adhered to regulation on the insulation and oversaw the build myself.
The glass has gas and e-coatings.

Do you reckon I'm doing well on the bill or poorly - I appreciate the comments
Click to expand...

properly designed.... they can...

You can see this theory happening with electric storage heaters... very popular in apartments.. they heat up on night time elec and dispearse the heat during the day....

It also the same principles by which houses were heated prior to any insulation.... ie castles etc.... large south facing openings allowed internal stone floors / walls to heat up during the day, and these stones emitted the heat through the night...
its not any kind of modern technology at work here.....
 
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