Vikings wrote: » Hi folks I've another what smart thermostat to buy post if anybody has any advice for me. Just moved house and want to upgrade the heating controls asap. Had previously used a single nest in previous house but thinking bigger. There's 10 rads in the house in total. 7 currently have TRVs fitted (excluding 2x bathroom and a vertical rad in kitchen) The current controller has CH and HW only - and somehow can't figure out how or why I can't just get the CH to work without the HW too.....
deezell wrote: » You should have at least one radiator open, and preferably before the zone valves. When the stove output exceeds the capacity of the HW cylinder to sink heat by gravity, the stove stat will close and turn on the stove pump. This will circulate the stove heat to any open rads in open zones. If all the rads have closed trvs, and all the zone valves are closed, this would prevent any rad dissipating the heat from the stove. Its moot to ask why a stove would be burning when there was no requirement for CH and the TRVs are all closed. What's required in this case is an open rad before the zone valves, or a relay triggered from the stove stat to open at least one zone. A lex or wiring box can be used to simplify mixed heat source systems, with a two pole relay used to turn on a zone valve or pump, and to mute the oil boiler call while the stove is producing excess heat. In such a system you would require a few open rads, or at the least to be running a schedule for the TRVs that would has some on call during the time the stove is burning. Again, TRVs do not suit a mixed source system as the possibility exists of all rads closed due to low temperature schedule, while someone lights a stove and cranks it up. Just using the stove stat to relay open a zone valve is not enough, if there are no open rads on this zone.
deezell wrote: » This is likely because your system is plumbed for gravity heating of the HW, and pumped heating of the CH. In this arrangement there are no zone valves, and the 2 zone controller uses a different logic...... Have a look to see what devices are in your circuit. Its possible you have zone valves if its a new or recent build, but the HW valve is either stuck open or locked open. This would cause HW to be on for any CH timed event.
Vikings wrote: » Thanks for taking the time for this - I've a better understanding of the system now. House was built around ~2000 so not new & not old either! I've had another look at things and can see I've a Horstmann Centaurplus C27 programmer which controls things. I noticed a separate switch within the hot press which can switch off the CH aspect from working via the controller. I don't think there are zone valves but I'll admit I'll need to take another look this evening to be sure. Having watched an install video or two on the Tado system it looks fairly straightforward to fit. And also easy to add smart TRVs at a later date. If you could answer another question for me re the Tado. If I was to install the starter kit with their TRVs I will have control similar to how my best used to work - whole house 1 temp? And if I add their TRVs I can have some control over each room it is in. If I do that, how do the rooms with no TRVs react to the settings? Will those rads go full blast?
deezell wrote: » Just have a couple of open rads. With Tado, you can schedule TRVs off grid, they will open but not call the boiler, just like a manual TRV. They'll still close though on hitting target. Technically a TRV is incompatible with an unregulated heat source, if the souce increases output greater than is necessary to bring the room to target temperature, the TRV does the exact opposite of a heat sink, by closing when it most needs to be open. My dual system is zone pumped, not valved. The stove stat turns on the ch zone pump, open rads heat the space, sometimes past the Tado stat setting, except in the kitchen which has a TRV. It would need to be blazing, or mild weather for it to heat past the schedule setting, but it does occasionally.
chris_ie wrote: » Yeah the plan at the minute is that I'd have a few open radiators in each zone without TRVs. Going to be fun trying to get an electrician who can wire this up right. You're not in Donegal by any chance deezell? I could leave the zone valves open and let the TRVs do the 'zoning' but then when stove isn't in use it'd be heating/pumping some places unnecessarily.
chris_ie wrote: » You're not in Donegal by any chance deezell?
deezell wrote: » What I wouldnt give for a few days in Dungloe, or Letterkenny. I haven't left Kildare for a year now, except back and forth to the city a few times. There's not much to the wiring, but a lex or wiring box will have all the relays you need to implement muting of oil and opening of zone valves by the stove stat. Nrg awareness do a lex box, https://www.nrgawareness.com/product/nrg-lex-v2-system-control-module/ Here's a good description if the one Systemlink do,https://www.systemlink.ie/systemlex.html
DrPhilG wrote: » I reckon I'd have nabbed him for a visit if he was .
chris_ie wrote: » Phil do you know if the Drayton has an off grid kinda setting like deezell mentioned the Tado has? Where it wouldn’t call for heat but would still close at the trv temp setting?
deezell wrote: » You can pop off the controller to see if its operating in gravity mode. Read page 3 of the installation sheet here.https://www.tlc-direct.co.uk/Technical/DataSheets/Horstmann/C21_I.PDF If the blue link mentioned is removed, its in gravity mode. Partial TRV installation will operate the heating for open rads also on a single zone system. It's useful nonetheless, as a means of reducing heat to selected rooms when not needed, bedrooms and lounge in daytime, kitchen later on etc. Also useful for cold rooms which might cool quicker than the general set temperature of the main stat.your existing mechanical TRVs will cap rooms not fittex with smart TRVs when the smart calls the boiler.
Vikings wrote: » Thanks again - after looking again it's the C21 there currently as the controller. There is something blue in that spot on the rear of the controller but I'm not sure if there was something additional covering it previously? If I've explained that properly. If I was to buy the tado starter kit - am I right to say I want the wired starter kit and also the extension kit for the water. Replace my C21 with the extension kit and replace wall thermostat with the tado smart stat. And then any/all trvs.
deezell wrote: » Tado Wireless starter kit from amazon .de for about €40 less than tado /iehttps://www.amazon.de/-/en/4260328611456-tado%C2%B0-Smart-thermostat/dp/B07FZ3P393
deezell wrote: » The mode link is a small blue blue jumper plug. I see what you're saying, it migh already be unplugged, leaving a similarly coloured receptacle. If you can't see an obvious small plug that you can grip and remove, if there is just a fixed socket receptacle with either pin holes or pins sticking out, then I'd assume it's already plugged out, and your controller is in gravity mode, with CH timer terminal 4 just controlling the pump, while the HW On teminal 3 fires the boiler for both CH and HW settings. Your Tado ext kit will replace this controller, it will have to be configured in gravity mode if that's what you have, which sounds likely for a circa 2000 build. Look again at the blue link, or its socket, post image if you can. You'll need what is known as the wireless starter kit, this incudes the ext kit, and if you don't already have a wired wall stat, you can connect the Tado stat wirelessly back to the ext kit. TRVs the next bit. If you want CH without HW, you'll need to add zone valves, but its not a biggie, HW is unlikely to overheat when the boiler is delivering heated water to the rads for CH, especially with the Tado, as it modulates the boiler burn for a cooler flow once the CH is near it's scheduled temperature.
DrPhilG wrote: » Ready to roll!
chris_ie wrote: » Good luck! Jees, looks like you have the same windows as me too!
sebdavis wrote: » How much they all cost in the end if you dont mind me asking?
DrPhilG wrote: » All in, system plus 2 room stats plus 15 TRVs, bit under €680 in total. Got some of the TRVs in a 3 pack, got a good few others second hand. Whole lot full price would be €800 ish.
sebdavis wrote: » Im trying to pick up the TRV's now.....the 3 pack was reduced in price and I missed it need to wait now
DrPhilG wrote: » In fairness it was only down by £5 for a 3 pack, so a pretty minor saving.
DrPhilG wrote: » All in, system plus 2 room stats plus 15 TRVs, bit under €680 in total. Got some of the TRVs in a 3 pack, got a good few others second hand. Whole lot full price would be €800 ish. Plus installation of course, which was fairly minor as I had both plumber and spark doing some other work too.
booooonzo wrote: » I have a honeywell evohome kit bdr91 wireless controller hot water kit 12 x HR92 I am installing a new cylinder and heating system and wanted to guide the plumber as to the best layout. he has never installed one before. Do i just continue with a basic S or y plan and install on that or is having multiple motorized valves also necessary? I assume I don't need the zone programmer or any of that. It will be upstairs and downstairs layout with separate hotwater What is the best approach for a new install or has anyone gone that route that could offer some guidance. eventually it will be new oil boiler direct to a new unvented cylinder and from there of to the rads or hw Is it still worth or necessary to zone the house with the 2 port valves? thanks
deezell wrote: » You wont need to zone the CH, but you will need a zone valve on the HW flow circuit if you want to independently control HW temperature. You should have 2 BDR91 receiver relays, one for all instances of CH calls from the controller stat and the TRVs. The other for calls from the HW thermostat kit. The HW relay will control the HW zone valve, whose built in relay will fire the boiler. This live out is combined with the live from the CH BDR91, together they fire the boiler for either HW or CH. If all rads are fitted with Evohome TRVs, then there is no requirement for a CH zone valve or it's relay. It's all in here, the diagrams show a single valve installation under Y plan, but do not reference the wiring required to activate the boiler for CH only. This would require the CH BDR91, as shown in the S plan.https://heatingcontrols.honeywellhome.com/Documents/All/pdf/evohome-installation-guide-(2020).pdf
Paulzx wrote: » I've all my downstairs rads fitted with Drayton TRV's. I originally started with the 2 zone and hot water thermostat kit for a few months. I've found the downstairs thermostat is now more or less redundant since i fitted all the rads with the smart TRV's. I still have standard non smart TRV's upstairs with the zone controlled by the Drayton Thermostat. I wonder can any long term users of the system give me another reason for still needing the Thermostat on the zone that is fully fitted with Drayton TRV's?