Should Loxone control my UFH and ASHP

[mattgibbs]

Hi everyone

 

our self build is pushing ahead and I am now looking into the Loxone system and will soon need to be Installing wet UFH followed by an ASHP.

 

As part of Loxone we will have a thermostat in each room as well as controlled blinds and I am wondering wether to bother with the Loxone value actuators and have Loxone control the heating for each room individually using the stats but short cycling is one of my concerns.

 

Or should I keeping heating and Loxone separate and not complicate something more than required.

 

Im interested to know your thoughts of how you think the best way to control the heating would be if you were using Loxone in your home.

[Thorfun]

I had similar thoughts to you when starting our journey. In the end I took the advice of many on here and our UFH is just one zone and is controlled by a wireless thermostat in our open plan kitchen. The house is a pretty constant temperature and there’s no need to adjust heating with individual room thermostats. 
 

obviously my Loxone switches tell me the temperature I just don’t do anything with it!

 

maybe one day I’ll see if I can get a wiring centre hooked up and average the temperatures of all the rooms to call for heat from Loxone. But, tbh, I doubt it. It works just fine as a simple heating solution. 

[JohnMo]

One of the issues with many zones will be very little engaged water volume, but more importantly nowhere for the flow to go.

 

You could do either of the below.

 

Run everything on weather compensation - no thermostat needed.

 

Have a manifold with no actuators or just a couple (ones likely to get loads of solar gain only). Run a slightly elevated WC curve or fixed flow temp. Have various thermostats, say bedrooms, living space, any cold area will start HP, heat all zones, all zones warm enough HP stopped. Basic thoughts are if one zone is getting cold others will follow, some time soon.

 

Depending on screed thickness reheat time be huge, especially at low flow temps. So it's better to drip feed heat into the floor. Waiting for a thermostat to call for heat could end up with yo-yo temps especially if the thermostat is quite large hysterisis. 

 

Other way depending on electric tariff is to batch charge floor. This takes a little trial and error, not hugely successful unless your heat pump is too big. When cold will need to run in more expensive periods. So if you have a 10kW HP you run for circa 6 hrs to get 60kWh of heat into the floor. You can do this with a 0.1 Deg hysterisis thermostat, just a matter of trial and error to fine times and set temperature.

 

You don't want a thermostat that run TPI mode with a heat pump, so make it's not operating in that mode.

[mattgibbs]

13 hours ago, Thorfun said:

I had similar thoughts to you when starting our journey. In the end I took the advice of many on here and our UFH is just one zone and is controlled by a wireless thermostat in our open plan kitchen. The house is a pretty constant temperature and there’s no need to adjust heating with individual room thermostats. 
 

obviously my Loxone switches tell me the temperature I just don’t do anything with it!

 

maybe one day I’ll see if I can get a wiring centre hooked up and average the temperatures of all the rooms to call for heat from Loxone. But, tbh, I doubt it. It works just fine as a simple heating solution. 

I’m glad you saw this post as I have gone back and read many of your comments regarding Loxone which has inspired me to do as much of the system as I can myself.

 

What you’re saying definitely sounds like the simplest solution and while Loxone is great, it does almost seem unnecessary for heating. I suppose I could still use the thermostats in the rooms to control the blinds to prevent overheating 

[mattgibbs]

12 hours ago, JohnMo said:

One of the issues with many zones will be very little engaged water volume, but more importantly nowhere for the flow to go.

 

You could do either of the below.

 

Run everything on weather compensation - no thermostat needed.

 

Have a manifold with no actuators or just a couple (ones likely to get loads of solar gain only). Run a slightly elevated WC curve or fixed flow temp. Have various thermostats, say bedrooms, living space, any cold area will start HP, heat all zones, all zones warm enough HP stopped. Basic thoughts are if one zone is getting cold others will follow, some time soon.

 

Depending on screed thickness reheat time be huge, especially at low flow temps. So it's better to drip feed heat into the floor. Waiting for a thermostat to call for heat could end up with yo-yo temps especially if the thermostat is quite large hysterisis. 

 

Other way depending on electric tariff is to batch charge floor. This takes a little trial and error, not hugely successful unless your heat pump is too big. When cold will need to run in more expensive periods. So if you have a 10kW HP you run for circa 6 hrs to get 60kWh of heat into the floor. You can do this with a 0.1 Deg hysterisis thermostat, just a matter of trial and error to fine times and set temperature.

 

You don't want a thermostat that run TPI mode with a heat pump, so make it's not operating in that mode.

I had not thought of doing it that way to be honest. Using the slab as a heat battery is an interesting idea but our heat pump won’t be oversized enough to do this.

 

how do you control the internal temperature if it gets to hot or cold when using weather compensation instead of a thermostat?

[Conor]

18 minutes ago, mattgibbs said:

 

 

how do you control the internal temperature if it gets to hot or cold when using weather compensation instead of a thermostat?

 

It doesn't really happen. We've ours set on weather comp on 7 hours per day (low rate overnight) with single stat set to 19.5c. During cold spells we just manually turn the heating on 24x7. There no need to control rooms individually.

 

As you can see, temperature only varies by 1-1.5c every 24hrs, sitting at an average 28.8c. peaks are either heating periods or having extra people in the house. The big trough was when I had to open the doors to vent the house after some pungent stir frying 

 

 

 

Edited Monday at 11:16 by Conor

[JohnMo]

4 minutes ago, mattgibbs said:

how do you control the internal temperature if it gets to hot or cold when using weather compensation instead of a thermostat

You should just be putting enough energy into floor to keep house stable. You will have to do some loop balancing during commissioning.

 

Or you just use thermostats as limit stops set a Deg or more above target temp only room that may get effected by solar gain. You don't want zones calling for heat just closing a few loops off. But UFH is pretty much self regulated. Floor temp is generally only a Deg or two above room temp. So if room gets two degs warmer than target (same temp as floor) floor output reduces to zero.

[Thorfun]

2 hours ago, mattgibbs said:

I could still use the thermostats in the rooms to control the blinds to prevent overheating 

yes! this is what i use mine for. 🙂 

 

although i override often in the winter as i want the rooms to heat up to save me heating them

Edited Monday at 13:29 by Thorfun
added the bit about winter