Underfloor heating: how to use properly

markin

Good window should not let in so much heat or it could be unbearable come summer. Is it the perfect temp on cloudy days?

What are you setting the temp to, and the current times?

Are you home all day?

What is the temp with no heating on at all, do you get lots of heat from the other flats?

If you want it warm at 9am then you need it on at around 5am, 2hrs to heat up and 2hrs to release most of the heat?


As a final resort, In a new, well insulated, small flat it may be easier to set it to 16c and use an electric heater to boost it to 18c on cloudy days?

 

Spir4

markin said:

Good window should not let in so much heat or it could be unbearable come summer. Is it the perfect temp on cloudy days?

What are you setting the temp to, and the current times?

Are you home all day?

What is the temp with no heating on at all, do you get lots of heat from the other flats?

If you want it warm at 9am then you need it on at around 5am, 2hrs to heat up and 2hrs to release most of the heat?


As a final resort, In a new, well insulated, small flat it may be easier to set it to 16c and use an electric heater to boost it to 18c on cloudy days?

 

It was sort of unbearable the last summer. This is our first year in this flat. It's a building from 2018 so the windows are definitely not old or cheap, but when you've got that much sun intake I think any window would struggle. Plus, in a way it's great, because it's loads of free heat in the winter. I just need to find a way to make it work with the UFH.
On cloudy days and an outside temperature of above 10 degrees, there's almost no need for heating. It stays above 20 degrees in the flat.

Another annoying thing is that the stats produce heat themselfs. So I have to set them about 2-3 degrees warmer for them to switch on the heat when it's actually a lot colder. This is how they're set:
22-23 degrees (then they switch on when the flast is 19-20 degrees, and off when it's 20-21 degrees)
The bedroom is set to 0 because we like a cold sleep.
The times I've been experimenting with are ON from 6-8am, 4-6pm and 8-10pm.

There's usually always someone at home all day.

The temp with no heating at all drops to about 19 degrees on normal days, but on the days it was freezing it dropped to 17 degrees. I'm not sure if we get heat from the other flats.

It's the warm floor that makes it nice and cosy. If I do as you say and let the heating do its thing 4 hours in advance, for 2 hours, the floors are already cold again by the time I need the heat.

Olly_J

Spir4 said:

Another annoying thing is that the stats produce heat themselfs. So I have to set them about 2-3 degrees warmer for them to switch on the heat when it's actually a lot colder. This is how they're set:
22-23 degrees (then they switch on when the flast is 19-20 degrees, and off when it's 20-21 degrees)

That's the thermostat hysteresis I would imagine, mechanical thermostats have always had this, turn on and off a degree or two either side of the set temp. if you have a digital state it might be adjustable, but there has to be some buffer, either time or temp, otherwise the boiler would be constantly switching on and off if it activated when it fell 0.1c below the set temp etc.

Also have you not thought about getting blinds\curtains so you can control the amount of sun coming through in summer?

70sbudgie

Have you tried a lower temperature for longer (or earlier)? Say 5am to 7am, 3pm to 9pm? Does it need to be on 3 times? I was trying to work out a longer pattern, but without knowing when you want the heat, found it tricky. 

At this time of year, if you don't have any window coverings, the heat will start escaping as the sun sets. So you probably want to set the heating to start warming about the same time, or a little earlier (hence my suggestion of 3pm). That way the floor is starting to feel like it is warming the room as the room starts to cool.

If the heating stat is low/off in the bedroom, you probably want the UFH to turn off the rest of the flat about half an hour before you go to bed.

You will need to keep tweaking until you've found the balance with how quickly your flat cools and when you want heat where. It sounds like you can vary the temperature for each room, but not the timing. That will take some coordination to get it right for you.

markin

The floors may feel cool again but the room would still be warm hopfully?

You may want to also look into getting the windows tinted professionally.

Spir4

Olly_J said:

Also have you not thought about getting blinds\curtains so you can control the amount of sun coming through in summer?

Yeah we've got curtains that don't let any light through, but when it's 40 degrees outside like we had last summer there's nothing that can keep that out, except AC. But summer is a whole different thing, I want to get winter sorted first now 

70sbudgie said:

Have you tried a lower temperature for longer (or earlier)? Say 5am to 7am, 3pm to 9pm? Does it need to be on 3 times? I was trying to work out a longer pattern, but without knowing when you want the heat, found it tricky. 

At this time of year, if you don't have any window coverings, the heat will start escaping as the sun sets. So you probably want to set the heating to start warming about the same time, or a little earlier (hence my suggestion of 3pm). That way the floor is starting to feel like it is warming the room as the room starts to cool.

If the heating stat is low/off in the bedroom, you probably want the UFH to turn off the rest of the flat about half an hour before you go to bed.

You will need to keep tweaking until you've found the balance with how quickly your flat cools and when you want heat where. It sounds like you can vary the temperature for each room, but not the timing. That will take some coordination to get it right for you.

5am to 7am and 3pm to 9pm is something I could try, but it feels like a waste to let the UFH run for longer than an hour or so because at that point it's just circulating hot water and not heating up anymore because the floor has already reached the temperature of the water. It feels more efficient to let it run an hour on, an hour off, and so on. But I can't do that with my programmer, it only lets me program 3 different schedules per day.

I'm sure I'll figure out something 

Spir4

markin said:

The floors may feel cool again but the room would still be warm hopfully?

You may want to also look into getting the windows tinted professionally.

Yeah that's also something we thought about. I just don't want to lose the "free" heat the sun provides in the winter 

Yes the room would still be warm, according to the thermometer. But because of the fact that the floors felt warm initially, and now cold, the actual perceived temperature is colder I think. A solution would be to wear slippers or something, but then I don't get the benefit from the nice warm floors when it is on.

Goooooooood 

DeeQS

Spir4 said:

Olly_J said:

Also have you not thought about getting blinds\curtains so you can control the amount of sun coming through in summer?

Yeah we've got curtains that don't let any light through, but when it's 40 degrees outside like we had last summer there's nothing that can keep that out, except AC. But summer is a whole different thing, I want to get winter sorted first now 

70sbudgie said:

Have you tried a lower temperature for longer (or earlier)? Say 5am to 7am, 3pm to 9pm? Does it need to be on 3 times? I was trying to work out a longer pattern, but without knowing when you want the heat, found it tricky. 

At this time of year, if you don't have any window coverings, the heat will start escaping as the sun sets. So you probably want to set the heating to start warming about the same time, or a little earlier (hence my suggestion of 3pm). That way the floor is starting to feel like it is warming the room as the room starts to cool.

If the heating stat is low/off in the bedroom, you probably want the UFH to turn off the rest of the flat about half an hour before you go to bed.

You will need to keep tweaking until you've found the balance with how quickly your flat cools and when you want heat where. It sounds like you can vary the temperature for each room, but not the timing. That will take some coordination to get it right for you.

5am to 7am and 3pm to 9pm is something I could try, but it feels like a waste to let the UFH run for longer than an hour or so because at that point it's just circulating hot water and not heating up anymore because the floor has already reached the temperature of the water. It feels more efficient to let it run an hour on, an hour off, and so on. But I can't do that with my programmer, it only lets me program 3 different schedules per day.

I'm sure I'll figure out something 

We're in a similar position to you. We moved into this house with wet UFH last January. We spent the first winter not ever really finding an acceptable way to heat the house and tried to use the heating like a traditional radiator system. This year we took a new approach.

We found setting the thermostats to be the desired temperature, and leave it permanently on used less energy in 24 hours than a timed system. We have south facing windows and, like you, in the sun in Winter they warm the house enough. We also had thermostats that weren't very smart and would read 2c higher than the room and wouldn't allow adjustment of the hystersis value.

I found that the heating would cycle on and off very infrequently. Once the floor was warm the residual heat kept the whole house warm and just a couple of 30minute bursts reheated the water enough to maintain the temperature. The only thing that annoyed me was the system running in the night so we upgraded all the thermostats to something we could program per room. Now we have different temps set per room on a timer for 8am-9pm and it works perfectly and is using much less gas than when I tried to do 3x 2-3 hours "bursts" each day.

Good luck! It took some getting used to but we got there.

Spir4

DeeQS said:

Spir4 said:

Olly_J said:

Also have you not thought about getting blinds\curtains so you can control the amount of sun coming through in summer?

Yeah we've got curtains that don't let any light through, but when it's 40 degrees outside like we had last summer there's nothing that can keep that out, except AC. But summer is a whole different thing, I want to get winter sorted first now 

70sbudgie said:

Have you tried a lower temperature for longer (or earlier)? Say 5am to 7am, 3pm to 9pm? Does it need to be on 3 times? I was trying to work out a longer pattern, but without knowing when you want the heat, found it tricky. 

At this time of year, if you don't have any window coverings, the heat will start escaping as the sun sets. So you probably want to set the heating to start warming about the same time, or a little earlier (hence my suggestion of 3pm). That way the floor is starting to feel like it is warming the room as the room starts to cool.

If the heating stat is low/off in the bedroom, you probably want the UFH to turn off the rest of the flat about half an hour before you go to bed.

You will need to keep tweaking until you've found the balance with how quickly your flat cools and when you want heat where. It sounds like you can vary the temperature for each room, but not the timing. That will take some coordination to get it right for you.

5am to 7am and 3pm to 9pm is something I could try, but it feels like a waste to let the UFH run for longer than an hour or so because at that point it's just circulating hot water and not heating up anymore because the floor has already reached the temperature of the water. It feels more efficient to let it run an hour on, an hour off, and so on. But I can't do that with my programmer, it only lets me program 3 different schedules per day.

I'm sure I'll figure out something 

We're in a similar position to you. We moved into this house with wet UFH last January. We spent the first winter not ever really finding an acceptable way to heat the house and tried to use the heating like a traditional radiator system. This year we took a new approach.

We found setting the thermostats to be the desired temperature, and leave it permanently on used less energy in 24 hours than a timed system. We have south facing windows and, like you, in the sun in Winter they warm the house enough. We also had thermostats that weren't very smart and would read 2c higher than the room and wouldn't allow adjustment of the hystersis value.

I found that the heating would cycle on and off very infrequently. Once the floor was warm the residual heat kept the whole house warm and just a couple of 30minute bursts reheated the water enough to maintain the temperature. The only thing that annoyed me was the system running in the night so we upgraded all the thermostats to something we could program per room. Now we have different temps set per room on a timer for 8am-9pm and it works perfectly and is using much less gas than when I tried to do 3x 2-3 hours "bursts" each day.

Good luck! It took some getting used to but we got there.

Thank you that's really interesting. I'll try that as well!

markin

leaving it on 24hr could be a problem depending on how your charged, If its simply time water is flowing, It will end up expensive, Now if you had the boiler in your control you could set the flow temp very low and use very little BTU's.