BotusBuild Posted Thursday at 19:36 Share Posted Thursday at 19:36 I have been left in a jam - I need your help to try to be in a position for the plumber to commission the ASHP etc. tomorrow. I bought the wrong type of thermostats and now want to make sure that what I can get at short notice (SF or Toolstation) will do the job. Setup: Wet UFH with actuators wired back to a wiring centre. All one zone so just the one thermostat controlling the lot. The wiring centre has four connections for the thermostat - L, N, a symbol with an arrow, and another one with what looks like a dial. The thermostat would appear to need to be able to send a signal to the wiring centre and my electrician has told me those latter two connections should connect to the thermostat on "clean" or "clear" contacts, and he also described them as being volt free. Does anyone have any recommendations if the following is not suitable I have found this at SF - Honeywell Home DT4 1-Channel Wired Room Thermostat. From the terrible installation manual I see this. Would the A/B <-> T1/T2 be volt free? Link to comment Share on other sites More sharing options...
JohnMo Posted Thursday at 19:58 Share Posted Thursday at 19:58 If you are operating single zone why the actuators? You need a pretty dumb thermostat nothing with TPI control just on or off, ideally with adjustable hysterisis. With UFH the thicker the screed the smaller the hysterisis you need. Otherwise you get big swings in temps - under and over target room temp. If you need a thermostat at all depends on how you intend to operate. Weather compensation? Fixed flow temp? Batch charge during cheap rates? Link to comment Share on other sites More sharing options...
BotusBuild Posted Thursday at 20:13 Author Share Posted Thursday at 20:13 It is what it is. I need a thermostat in there right now. I need answers to my questions, not more questions. Sorry that your response may have factual info in it, but right now, none of that helps me. Link to comment Share on other sites More sharing options...
Nickfromwales Posted Friday at 00:19 Share Posted Friday at 00:19 4 hours ago, BotusBuild said: It is what it is. I need a thermostat in there right now. I need answers to my questions, not more questions. Sorry that your response may have factual info in it, but right now, none of that helps me. Easy tiger Anyone on here who is asked to advise at short notice will either ignore you or do the honourable thing and ask for some rudimentary information to base a reply upon. "Tomorrow" is only going to happen if you compromise and cross your fingers, so why is the deadline so immovable? You ask if the above is zero volt, and from what I see the answer is yes. With the square root of feck all info to go on, I assume these are battery powered stats? If so, you can use them in your suggested scenario above. If you get properly stuck tomorrow, PM me your mobile number and I'll talk you through some options / give tech support as best I can. Hope that helps. Link to comment Share on other sites More sharing options...
Eric Posted Friday at 00:46 Share Posted Friday at 00:46 19 minutes ago, Nickfromwales said: Easy tiger If you get properly stuck tomorrow, PM me your mobile number and I'll talk you through some options / give tech support as best I can. Good advice from Nick & very generous offer of help. There will be a solution, I’m sure the heat pump can be run without the thermostat. The most important thing to do is PM me Nicks number once you get it, I need to start my plumbing very soon & I need him on speed dial 😉😬 Link to comment Share on other sites More sharing options...
Nickfromwales Posted Friday at 00:49 Share Posted Friday at 00:49 2 minutes ago, Eric said: Good advice from Nick & very generous offer of help. There will be a solution, I’m sure the heat pump can be run without the thermostat. The most important thing to do is PM me Nicks number once you get it, I need to start my plumbing very soon & I need him on speed dial 😉😬 You can't afford me lol. I have a wife, 4 kids, and an AMG to feed 1 Link to comment Share on other sites More sharing options...
Eric Posted Friday at 00:52 Share Posted Friday at 00:52 2 minutes ago, Nickfromwales said: You can't afford me lol. I have a wife, 4 kids, and an AMG to feed Living with the in-laws I can’t not afford you Nick 😎 Link to comment Share on other sites More sharing options...
Temp Posted Friday at 00:55 Share Posted Friday at 00:55 The DT4 appears to be capable of either mains power with battery backup or just battery operation. The two outputs A an B do appear to be volt free. So based on what you said I think that ones OK. It does appear to be a bit simple. For example I don't think you can program it to drop the temperature a few degrees at night or while out at work but I don't know if thats appropriate for ASHP systems. Link to comment Share on other sites More sharing options...
Nickfromwales Posted Friday at 00:55 Share Posted Friday at 00:55 2 minutes ago, Eric said: Living with the in-laws I can’t not afford you Nick 😎 Ouch….I mean, you lucky chap to have such wonderful landlords. 🤣🤣🤣🤣🤣🤣🤣 Link to comment Share on other sites More sharing options...
Nickfromwales Posted Friday at 01:01 Share Posted Friday at 01:01 7 minutes ago, Temp said: The DT4 appears to be capable of either mains power with battery backup or just battery operation. The two outputs A an B do appear to be volt free. So based on what you said I think that ones OK. It does appear to be a bit simple. For example I don't think you can program it to drop the temperature a few degrees at night or while out at work but I don't know if thats appropriate for ASHP systems. Exactly why this needed time and info for any kind of discernible response If tomorrow is immovable then I’d say buy the cheapest stats (£10 Honeywell rotary’s) and bin them later once an opportunity to decide on the final equipment has had a chance to evolve. “setback” thermostats will be a necessity with UFH, but a lot of (even shite) modern controls can achieve this as they don’t turn “off/on” but instead toggle between “comfort” and “economy” by you being able to select temps at chosen times; to do this you set to 18.5°C from 23:00 to 05:30, then 20.5°C from 05:31 to 07:30, and so on (assuming a working week). Ideally you’d need / want a stat that does 5+2 (mon-fri, then sat & sun), ergo this needs to be discussed properly and not with someone giving “24 hrs notice” 2 Link to comment Share on other sites More sharing options...
BotusBuild Posted Friday at 07:03 Author Share Posted Friday at 07:03 Thank you all, and apologies for being short. It was a long frustrating day. 1 Link to comment Share on other sites More sharing options...
Conor Posted Friday at 07:12 Share Posted Friday at 07:12 Just use a bit of copper wire to jump the volt free terminal on the unit. It'll get you working. The ashps own timer, flow temp, and weather comp settings will allow you to control the heat in the house. 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted Friday at 10:49 Share Posted Friday at 10:49 3 hours ago, BotusBuild said: Thank you all, and apologies for being short. It was a long frustrating day. 50 lashes seems both fair and appropriate. Link to comment Share on other sites More sharing options...
BotusBuild Posted Friday at 18:24 Author Share Posted Friday at 18:24 7 hours ago, Nickfromwales said: 50 lashes seems both fair and appropriate. Do the ones I was subjected to during the week count? 🙂, and thanks for your kind offer to be on the end of a phone. 11 hours ago, Conor said: Just use a bit of copper wire to jump the volt free terminal on the unit. My electrician did this via a switch, so the installer was able to commission today. Over the weekend or early next week I'll swap that out for a thermostat. They've set all the actuators to manual (open) on the one manifold we have loops connected to, and we've deactivated the hot water and its setup to gradually changing the flow temperature over the next week. All the loops are embedded in the foundation slab (250mm) which sits on top of Jackon Atlas insulation (300mm if I recall correctly) which has been in for 4+ years so should already be fairly dry. Next week I'll be getting a temporary kitchen and bathroom setup for when we camp out there in February (long story) so both the heating and the hot water are going to be tested. Pics next week if I remember. 1 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted Friday at 20:58 Share Posted Friday at 20:58 2 hours ago, BotusBuild said: which has been in for 4+ years so should already be fairly dry. Lol. If it ain't dry by now it's never going to be Link to comment Share on other sites More sharing options...
Benpointer Posted Saturday at 08:43 Share Posted Saturday at 08:43 On 17/01/2025 at 01:01, Nickfromwales said: Exactly why this needed time and info for any kind of discernible response If tomorrow is immovable then I’d say buy the cheapest stats (£10 Honeywell rotary’s) and bin them later once an opportunity to decide on the final equipment has had a chance to evolve. “setback” thermostats will be a necessity with UFH, but a lot of (even shite) modern controls can achieve this as they don’t turn “off/on” but instead toggle between “comfort” and “economy” by you being able to select temps at chosen times; to do this you set to 18.5°C from 23:00 to 05:30, then 20.5°C from 05:31 to 07:30, and so on (assuming a working week). Ideally you’d need / want a stat that does 5+2 (mon-fri, then sat & sun), ergo this needs to be discussed properly and not with someone giving “24 hrs notice” Quick question, and apols for taking this away from Botus's original crisis, but with UFH why wouldn't you just leave it on at a comfortable temperature 24x7? As I understand it Botus is doing a well-insulated new build. Link to comment Share on other sites More sharing options...
JohnMo Posted Saturday at 16:28 Share Posted Saturday at 16:28 7 hours ago, Benpointer said: but with UFH why wouldn't you just leave it on at a comfortable temperature 24x7? Good question. On a flat rate tariff, the ideal is run weather compensation, no need for thermostat. On a time of use tariff, you may what to trigger heating events. I use a thermostat as a conditional timer, to make use of E7 tariff at night. Generally the rest of the time the heat pump is off. But for me (thick screed) I use a 0.1 Deg hysterisis thermostat to stop under and over swings in house temperature. 1 Link to comment Share on other sites More sharing options...
Benpointer Posted Saturday at 22:08 Share Posted Saturday at 22:08 How thick is your screed JohnMo? Link to comment Share on other sites More sharing options...
JohnMo Posted Saturday at 22:26 Share Posted Saturday at 22:26 18 minutes ago, Benpointer said: How thick is your screed JohnMo? 100mm fibre reinforced concrete, instead of screed. 1 Link to comment Share on other sites More sharing options...
BotusBuild Posted Sunday at 14:18 Author Share Posted Sunday at 14:18 I do intend to run the heating 24x7 with weather compensation. Indeed that is how it is now running, while the 250mm slab gets warmed up. The room thermostat will be there to control when the heating pump comes on and the actuators open on the loops. Currently all actuators are manually opened, but will be switched back to Auto at a later date. We elected to go for a buffer tank setup so that if we wanted to zone this downstairs (bedrooms etc) into separate zones by adding extra thermostats we could do so without major plumbing rework. 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted Sunday at 14:24 Share Posted Sunday at 14:24 5 minutes ago, BotusBuild said: I do intend to run the heating 24x7 with weather compensation. Indeed that is how it is now running, while the 250mm slab gets warmed up. The room thermostat will be there to control when the heating pump comes on and the actuators open on the loops. Currently all actuators are manually opened, but will be switched back to Auto at a later date. We elected to go for a buffer tank setup so that if we wanted to zone this downstairs (bedrooms etc) into separate zones by adding extra thermostats we could do so without major plumbing rework. Nice neat install 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted Sunday at 14:27 Share Posted Sunday at 14:27 On 18/01/2025 at 08:43, Benpointer said: Quick question, and apols for taking this away from Botus's original crisis, but with UFH why wouldn't you just leave it on at a comfortable temperature 24x7? As I understand it Botus is doing a well-insulated new build. The scientific answer to that, is, I just forget who’s building what and reply here sporadically….lol….but I tend to offer free advice with an assumption that covers the worst case. 20,000+ members on here now, and I am so busy I can just about remember what colour shreddies I am wearing. The 24/7 setback stats can (usually) be set to ‘manual override’ too, which ticks every possible box. Link to comment Share on other sites More sharing options...
Bramco Posted Sunday at 16:24 Share Posted Sunday at 16:24 (edited) 2 hours ago, BotusBuild said: I do intend to run the heating 24x7 with weather compensation. Indeed that is how it is now running, while the 250mm slab gets warmed up. The room thermostat will be there to control when the heating pump comes on and the actuators open on the loops. Currently all actuators are manually opened, but will be switched back to Auto at a later date. We elected to go for a buffer tank setup so that if we wanted to zone this downstairs (bedrooms etc) into separate zones by adding extra thermostats we could do so without major plumbing rework. Is that an ASHP throne I see there? Better not show it to ours, in case it gets the hump and wants us to build one for it. Edited Sunday at 16:25 by Bramco Made picture more obvious 1 1 Link to comment Share on other sites More sharing options...
BotusBuild Posted Sunday at 17:08 Author Share Posted Sunday at 17:08 Just a plain old gabion (2x1x1m) with a 4 inch concrete slab poured on top with a condensate pipe embedded. The ground behind and to the side will be backfilled so it will be more at ground level in time. The side of the gabion you can see here will be th start of a pathway down the side of the house which is partially buried. Link to comment Share on other sites More sharing options...
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