Ufh efficiency

[Pocster]

My Wet ufh below ground has 6 zones . I’ve setup my automation to come on/ off when above / below temperature.

Is it more efficient to have more zones on to heat the area rather than fewer ?

I’m not worried about time to get to temperature.

Also I can set the pump to a lower speed .

 

So fewer areas ( open plan ) on at once ? . Pump lower speed ? . What combination is most efficient?

[Ralph]

We're very open plan.The company that set up my system said they have found that simplifying to a single zone, or as few as possible gives the best efficiency. 

 

We have a single zone that includes the UFH downstairs and the four rads upstairs. 

 

[Pocster]

2 minutes ago, Ralph said:

We're very open plan.The company that set up my system said they have found that simplifying to a single zone, or as few as possible gives the best efficiency. 

 

We have a single zone that includes the UFH downstairs and the four rads upstairs. 

 

So I should put on as few zones as possible . Lower the pump speed ? . My concern is at a lower pump speed the temperature required might never be met so the pump is continuously running .

[jayc89]

We have 7x loops and had 3x zones. Over summer I changed that a single zone. I haven't notice any obvious difference in efficiency. I had to increase the pump speed to get the flow rates set correctly as it was having to serve all loops at the same time, which it previously might not have had to do. 

 

I've also started playing with the temp differential (i.e how low below the target temp before the stat calls for heat). For some reason my stat was set to 0.5c (even though the manual says the default is 1c) and I found the boiler to be turning on every 30 mins. I've dropped it to 1c and it's now coming one once an hour, so a difference but I'll need to wait a couple of days to see whether it's actually made it more efficient to run...

[JohnMo]

Single zone with weather compensation.  With night time setback of a couple of degrees.  Have the thermostats set slightly higher than the target room temp of 20, to keep the UFH manifold pump on.  Bedrooms temps are 18, set by slowing the flow rate to those rooms.

 

Last year I worked out the how long the floor takes to heat up and set start time and end time of the day time temp around it, so starts at 0230 and at 1830.

 

My current flow temps are around 23 degrees.  According to the boiler datasheet, I should be getting around 110% efficiency.  Not sure how true that is.

 

Gas usage including DHW is averaging around 15/16kWh a day over the last 10 days in NE Scotland.

[jayc89]

40 minutes ago, JohnMo said:

Single zone with weather compensation.  With night time setback of a couple of degrees.  Have the thermostats set slightly higher than the target room temp of 20, to keep the UFH manifold pump on.  Bedrooms temps are 18, set by slowing the flow rate to those rooms.

 

Last year I worked out the how long the floor takes to heat up and set start time and end time of the day time temp around it, so starts at 0230 and at 1830.

 

My current flow temps are around 23 degrees.  According to the boiler datasheet, I should be getting around 110% efficiency.  Not sure how true that is.

 

Gas usage including DHW is averaging around 15/16kWh a day over the last 10 days in NE Scotland.

 

Jeez I use half that just heating our DHW

 

250L tank, couple of showers a day, pressure is around 3bar so it only takes a 15 minute shower to empty the tank.

[JohnMo]

Last Oct I used an average 44kWh per day, mostly due to short cycling.  Fixed that over the summer with some system modes and setting up WC with a few calculations and a bit of fine tuning.  House is also very well insulated.