UFH - EvoHome and reluctant plumber
Collapse
X
-
Originally posted by kevinsmart View PostWhat schedule and set points are you typically using for your UFH zones? Are you combining with rads via a lower temp mixing valve? Using OpenTherm?
sensors ) . No open therm. Input temp to ufh mixing sysyem 65-70 deg Manifold output temp approx 45deg. Manifold return temp approx 38deg. HCC80 ufh controller , operating 2 zones with 7 pipe runs of 80 Metres. However each set up is goîng to vary quite a bit. If pipe length are similar it makes settîng up of the flow rates easier to get to the in/out temp differentials. We also have a separate safety thermostat attached to the manifold output set to shut down the whole ufh system if it gets to 50deg. This is to protect the floor but also for health issues. Too high ufh temp can be bad for some people’s circulation.Last edited by rvb99; 26 February 2019, 09:58 PM.
Comment
-
-
Originally posted by kevinsmart View PostWhat schedule and set points are you typically using for your UFH zones? Are you combining with rads via a lower temp mixing valve? Using OpenTherm?
Comment
-
-
I think the key difference is that I am only heating our UFH zone in the evening. In an experiment, running 24/7, Evohome could maintain a stable temperature when the set point was set to the current temperature.
It doesn’t matter if the temperature differential is 3 degrees or only 0.5 degrees when heating starts, by 9pm when optimum stop kicks in the zone is 1 degree above the set point.
Comment
-
-
Originally posted by kevinsmart View PostI think the key difference is that I am only heating our UFH zone in the evening. In an experiment, running 24/7, Evohome could maintain a stable temperature when the set point was set to the current temperature.
It doesn’t matter if the temperature differential is 3 degrees or only 0.5 degrees when heating starts, by 9pm when optimum stop kicks in the zone is 1 degree above the set point.
Comment
-
-
Originally posted by mtmcgavock View PostWhy are you only running it in the evening? You aren't meant to run UFH for short periods otherwise you won't get the correct heat out of it. In effect you are heating a big surface area that holds it's heat. Heating it for short periods you are never going to get the correct temperatures. You can't operate it like radiators.
I expected much better temperature control from Evohome. It copes well with HR92 zones, but is unable to adapt to my UFH zone. I could program a Raspberry Pi to do a better job. 😀
Comment
-
-
Hope you don't mind me carrying on with the BDR91 vs HCC80 theme. I am about to add UFH to my existing Evohome system that has 11 Rads with HR92s fitted and it works well. I have a 4 port manifold for UFH for a kitchen and utility room, 3 pipe runs for kitchen (72m, 80m, 81m) & Utility 67m. I was thinking about using 1 BDR91 running the 4 ports as 1 zone with a UFH pump and a mixer valve. There is no motorized zone valve or actuators other than manual adjuster on the manifold.
If I wired the BDR to switch on the UFH pump for all the ports on the manifold and control the temperature with a Y87RF thermostat would this work ok? Thanks in advance - I hope I haven't hijacked the thread!
Comment
-
-
Originally posted by kevinsmart View PostI have a single zone twin loop UFH setup controlled via Y87RF and BDR91 in my new well insulated extension. BDR91 activates the pump and manifold valves are left open.
As it’s in combination with 26 rads, there is a thermostatic mixing valve to reduce the flow temperature. Boiler is Intergas HRE40 SB with OpenTherm module, and an outdoor sensor (unfortunately weather compensation doesn’t work with Evohome OpenTherm support though).
I’m not happy with the UFH setup for a few reasons:
1. The mixing valve intermittently emits a high pitched whine, appears to be when the flow temperature matches its set point.
2. Wife complains about 1!
3. Poor temperature control. Evohome indicates a 40-60% demand for the zone even when the set point is reached, as a result there is an overshoot. Optimum start typically pre-heats for 1.5 hours, temperature increases to more than 1 degree above the set point after a few more hours, still with <20% demand, then optimum stop kicks in 1 hour before set back. I’ve tried reducing the mixing valve set point temperature but Evohome seems unable to adapt.
Primarily because of 2, I’m going to replace with an HM80 controlled rotary actuator and flow temperature sensor. I hope this will work better with OpenTherm and provide more accurate temperature control.
It's entertaining watching the controller make quiet regular small adjustments to the rotary valve to maintain temperature.
One interesting observation was this freezing morning with a 15C setback temperature and 15.5C measured temperature, the controller decided to run the pump, with Evohome indicating a 0% heating demand (but other zones heating). This appeared to stop further heat loss in the zone.
Comment
-
-
Hope you don’t mind me piggy backing on this, but I have wet UFH as a single zone, two loops controlled using a zone valve set up. It’s in conjunction with the rest of the house on radiators. The system runs on optimum start.
My question is about scheduling. With the temp drop over the last few days, it’s taken a while on warm up. Normal temp is 20degs, with a setback to 17degs when we’re not using the room. Last night it didn’t hit its set temp, only getting to 19degs.
Is it best to have the schedule adjusted to get this the sole priority when warming up? My feeling is that it shouldn’t matter as the water temps are significantly lower than to the rest of the system. Or do you think it’s the optimum start that’s causing the issue, because of the large lag with the heat cycle?
Cheers,
Ian
Comment
-
-
Originally posted by kimber.kimber View PostHope you don’t mind me piggy backing on this, but I have wet UFH as a single zone, two loops controlled using a zone valve set up. It’s in conjunction with the rest of the house on radiators. The system runs on optimum start.
My question is about scheduling. With the temp drop over the last few days, it’s taken a while on warm up. Normal temp is 20degs, with a setback to 17degs when we’re not using the room. Last night it didn’t hit its set temp, only getting to 19degs.
Is it best to have the schedule adjusted to get this the sole priority when warming up? My feeling is that it shouldn’t matter as the water temps are significantly lower than to the rest of the system. Or do you think it’s the optimum start that’s causing the issue, because of the large lag with the heat cycle?
Cheers,
Ian
Comment
-
-
Originally posted by kevinsmart View PostIan, you can configure how many hours optimum start will pre-heat, maybe you need to increase that parameter.
I'm assuming even when you add a new zone, the learning still takes place, and it is continually learning, taking into account the conditions?
Comment
-
-
I started out with my wet UFH plumbed into a radiator circuit but was never completely happy with its controllability. I know in theory that it should be independent and fine if all rads have HR92s fitted, it seems to behave perfectly now it's plumbed back directly to the boiler. Temperatures are maintained to +/- 0.5 and optimum start and stop set to 1hr work really well. The ufh zone is flagged so there's real opportunity for overshoot but the optimised stop seems to handle this.
Comment
-
Comment