Those with underfloor heating. Boiler run times?

Mat the trasher

Hi, I'm trying to optimise a underfloor system for a friend and at the moment they are running the zones and boiler for 8-10 and 17-22hrs, which I think is more or less pointless.
Advising to run the living zone 24hr, using a 3 degree set back temp at night, and bedrooms, 6-8 & 17-20, no set back.
not sure what way to run idle rooms, just to keep them aired.

living area temp setpoint 21
bedroom temp setpoint 17-18
idle rooms temp setpoint 15?

I'm also interested in reaction time were for example, increasing the thermostat in an idle room to use it. how many degrees per hr increase.

Insulation standard is good.
Boiler output temp is 60C, will increase it to 70.

I know all zones should be 24hrs on with each on thermostats, however the zones are large and some zone areas are more or less idle

TPM

Mat the trasher wrote: »

Hi, I'm trying to optimise a underfloor system for a friend and at the moment they are running the zones and boiler for 8-10 and 17-22hrs, which I think is more or less pointless.
Advising to run the living zone 24hr, using a 3 degree set back temp at night, and bedrooms, 6-8 & 17-20, no set back.
not sure what way to run idle rooms, just to keep them aired.

living area temp setpoint 21
bedroom temp setpoint 17-18
idle rooms temp setpoint 15?

I'm also interested in reaction time were for example, increasing the thermostat in an idle room to use it. how many degrees per hr increase.

Insulation standard is good.
Boiler output temp is 60C, will increase it to 70.

I know all zones should be 24hrs on with each on thermostats, however the zones are large and some zone areas are more or less idle

This isnt an easy one.

if you are room stats you are not going to get great results by only running the boiler for limited periods.
TBH IMO the whole set up will be determined by:
The depth of screed over the pipes
the pipe centers
the individual loop length
the concentration of pipe (meters of pipe per sqm of floor)
the water temperature
how well the house is insulated.

If you had this information or even some of it you could make a decent stab at it

That said you basically have 2 options
1) Leave the boiler running all the time and let the stats control the heat, this will generally use a lot of oil if there is no thermal store fitted

2)run the heating in the whole house or each area for a few hours a few times a day to maintain the required temperature, it takes a bit of time to set up though(eg heating on from 5am to 7am, again from 12pm to 1:30pm then from 6pm to 9pm, you use the flow control on each zone to balance the heat in each room similar to rads), I have had some decent results with set ups like this.

The problem with using room temperature control and limited boiler running is that some times when the boiler is due to run certain rooms may not be calling for heat and by the time they do call for heat the boiler could be off so no heat will be available.

In general with the systems installed in ireland the secret to any sort of economical running is maintaining the temperature of the building structure not just the room temperature

Mat the trasher

Agree with you TPM. Idealy I would install a buffer tank and have a daily room sat in every room, controlling the the manifold operation and sending a demand to the zone pump. But that would cost 2 grand without installation I reckon. Nevermind the wiring problems. Its a large house 4 manifold zones and pump sets and some rooms have 4 ufh circuits.
I can never understand how complicated housing heating systems in this country are half assed installed, particulary in this case I know the budget was there to have it properly controlled. I guess oil was cheap then!!

TPM

people spent a fortune putting in heating and control systems, but most of these were not good value as for the sake of a few percent combined with the lack of information in this country the systems fell short of what they needed to be.

unfortunately with underfloor heating if there isnt enough pipe in the floor there isnt alot you can do with it.

oil may have been cheaper but it was still a case of a poor underfloor system using 5-6 fills of oil versus 2-3 with rads.

I do think done properly it is a great job but there is no half measures of shortcuts from the design stage up.

do you know the depth of the screed in this case?

Mat the trasher

I don't have a screed depth, prize to the first person to say drill it for depth:eek:. I do have the layout plan for all the circuts, all 26 of them, I do reckon there is enough of them. Its just if the house was fully occupied all the time then ok run them all, but I'd hate to be filling the tank! Reckon 500-600l per/month in the winter months.

TPM

If there is a deep screed it could use more oil letting it cool down and heating it up again than maintaining the temperature(could keep it low enough), some UFH systems have a brutal response time
any UFH I have been involved with(even if i was only doing the boiler) I went around and took photos or videos of the finished pipework some times they didnt have any relation to the layout plans at all.

This is where someone usually pops up and suggests thermal imaging