Best Wifi enabled thermostat
Discussion
clockworks said:
If I bypass the 2 port valve in the wiring centre (relay switched live to existing 2 port valve switch output connection, disconnect 2 port valve wires), is it best to try and remove the 2 port valve control box, or just remove the return springs and open the valve manually?
It's a Honeywell valve with the pip on the cover, so it should be removable .
IMO just leave it in place and open the valve manually. If it’s electrically isolated it won’t try to close. If you have HR92s on all rads there should be no risk of rads heating up, obviously HW demand will cycle round the CH supply pipes but that shouldn’t cause an issue as no radiators will actually heat up.It's a Honeywell valve with the pip on the cover, so it should be removable .
clockworks said:
My plan was to just replace the 2 port valve or control head. It might be a good idea to do this still, so as not to confuse future owners. That would also mean we could remove the Evohome setup and sell or reuse it when the house is sold, reinstating the original programmer and TRVs. The house is on the market.
I think if you’re selling it would be fair to leave the new owners with a standardised configuration, I’d personally return to S-Plan and leave the controller with the house configured as a whole zone + refit TRVs. Up to you if you want to fix the sticky valve 
essayer said:
Uncool said:
4) When you say 'lock open' is that electronically, or do I physically remove the 2 way valve head and remove it from the circuit, and just manually spin the valve open? I'll be replacing all the valves on the rads too with up to date honeywell jobbies as I have these awful dual entry microbore things that you can't even buy anymore.
Really appreciate your help with this, thanks!
Permanently open, uncontrolled. There’s different schools of thought, depending on how you have things configured.Really appreciate your help with this, thanks!
If you fit a boiler relay, you don’t need to have a CH relay, you can leave the valve opened mechanically and electricals isolated; or you can just wire the valve to mains so that whenever the system is powered, the valve is open; not sure what happens if you just remove the head, but either way there is no need to open/close the CH system as that task has now moved to all the individual TRVs.
If you don’t fit a boiler relay, then the boiler needs to be fired from the CH or DHW valves being fully opened; same as a S plan system. I think in this case evohome will operate the CH valve and/or DHW valves as required.
On the point about the leaving the CH valve open, I think I'd prefer it if it were opened by the evohome, because otherwise there's a lot of heat going round the pipes when the HW is on but the CH is off (like in summer). Presumably this'll work too? And the valve will then trigger the boiler to fire?
Really appreciate you taking the time here.
Uncool said:
Great, thanks, so I think I'm nearly there.
On the point about the leaving the CH valve open, I think I'd prefer it if it were opened by the evohome, because otherwise there's a lot of heat going round the pipes when the HW is on but the CH is off (like in summer). Presumably this'll work too? And the valve will then trigger the boiler to fire?
Really appreciate you taking the time here.
It wouldn’t be my preference, mainly because the valve will continually open and close at times of partial load; like most Honeywell kit Evohome implements TPI, which pulses the boiler on and off to meet the perceived demand. You’ll hear the valve opening and springing closed every five minutes which can get annoying.On the point about the leaving the CH valve open, I think I'd prefer it if it were opened by the evohome, because otherwise there's a lot of heat going round the pipes when the HW is on but the CH is off (like in summer). Presumably this'll work too? And the valve will then trigger the boiler to fire?
Really appreciate you taking the time here.
I don’t think having heat in the pipes is too bad, remember that the valves will all be closed if there is no HW demand, so the only flow of hot water will be on the supply sections of pipe which go back to the boiler anyway.
The way mum's system is wired, the two BDR91s are wired to supply a live feed to the motor on a 2 port valve. The switch in the valve is then wired to supply power to the boiler and pump as with the old programmer. That's the way Honeywell say to implement S plan in the manual. It's a basic oil boiler - external pump and expansion vessel. No overrun timer. There's an automatic bypass valve.
All radiators have Evohome TRVs, except for one which isn't used, and has both valves closed. It should be fine with the CH valve locked open.
Mum has ordered a replacement Honeywell 2 port valve, so I'll replace the control head. If the actual water valve is sticking, I'll get a plumber to replace the valve (I don't fancy draining and refilling, and access to the valves is tight). Getting it all working properly leaves us with the option of reverting to the old programmer and mechanical TRVs if the house gets sold and the new owners don't want to pay a bit more to keep it.
Someone asked about using two Honeywell TRVs in one room, configured as a single zone - how to set one radiator to a lower temp than the other.
It's possible to calibrate each TRV individually (plus and minus 3 degrees, I think), so the "slave" could be set to over read by a couple of degrees. It would close earlier on it's own, but the controller wouldn't be bothered. It will set the temperature of both valves, but only take a room reading from the "master" valve.
Fitting Evohome to mum's system has shown up a few existing problems. Two of the TRV bodies wouldn't fully close (replaced with new ones), and the boiler locked out a lot more than it did before (poor spark, replaced the igniter transformer). Now the 2 port valve is sticking. I guess everything is getting cycled a lot more than it did with the old programmer, mechanical TRVs, and no room stat.
The boiler/pump used to run all day, just switching off at night. Water circuit temperature was "regulated" by the thermostat on the boiler, which was set at not far off maximum. Dad didn't believe in having a room stat, and they never closed the room doors, so never noticed the sticking TRVs. No wonder they were using well over 2000 litres of oil a year in a 3 bed, well insulated, bungalow. I expect consumption to be halved with Evohome, so it'll pay for itself in 2 years.
Thanks for your insights clockworks.
I'm intrigued that you and essayer differ on how to wire the CH circuit - either 'always on' at the two-way valve and just using the BDR91 to switch on/off the boiler, vs having the BDR91 operate the two-way valve and that call the boiler/pump. I can see the advantages / disadvantages of each.
You say that's how Honeywell say to do it, but a Google around suggests that both methods are recommended. The installation guide is amazing light on detail on this part..
Any idea where the Honeywell recommendation is?
I'm intrigued that you and essayer differ on how to wire the CH circuit - either 'always on' at the two-way valve and just using the BDR91 to switch on/off the boiler, vs having the BDR91 operate the two-way valve and that call the boiler/pump. I can see the advantages / disadvantages of each.
You say that's how Honeywell say to do it, but a Google around suggests that both methods are recommended. The installation guide is amazing light on detail on this part..
Any idea where the Honeywell recommendation is?
I just followed the wiring diagrams in the Evohome installation manual that came with the controller. It's available online here: http://www.honeywelluk.com/professional-zone/resou...
I'm in no way a plumber or spark, just a reasonably competent DIYer. My dad was a spark, so I've messed around with electrics since I was old enough to hold a screwdriver (50 years plus).
A lot of the work that I've done has been out of necessity, as finding a competent tradesman can be be difficult. Plumbers that won't touch anything with wires, sparks who can't read a simple diagram, boiler engineers who can't fault find. There are good people out there (and on here), it's just hard to find them sometimes.
The plumber who mum called to sort out her duff TRV bodies told her she should leave the valve permanently open because the system needed an open radiator for safety. It seemed to escape him that he had installed the mechanical TRVs 12 years earlier, along with an automatic bypass valve.
The spark that put in the Evohome relays did a neat job, just connected the wires up wrong. Caused me a bit of headscratching when I tried to configure the system. 5 minutes with a screwdriver and the manual sorted it.
Boiler engineer spent quite a few hours messing about with the flue and air inlet pipe, rather than swapping the igniter and fixing the weak spark. Thanks to advice from a PHer, I fixed it.
Sometimes it's just easier to do some research, take advice from someone who knows (there's generally someone on PH who can help), and get stuck in and fix it yourself. Immensely satisfying, too.
I'm in no way a plumber or spark, just a reasonably competent DIYer. My dad was a spark, so I've messed around with electrics since I was old enough to hold a screwdriver (50 years plus).
A lot of the work that I've done has been out of necessity, as finding a competent tradesman can be be difficult. Plumbers that won't touch anything with wires, sparks who can't read a simple diagram, boiler engineers who can't fault find. There are good people out there (and on here), it's just hard to find them sometimes.
The plumber who mum called to sort out her duff TRV bodies told her she should leave the valve permanently open because the system needed an open radiator for safety. It seemed to escape him that he had installed the mechanical TRVs 12 years earlier, along with an automatic bypass valve.
The spark that put in the Evohome relays did a neat job, just connected the wires up wrong. Caused me a bit of headscratching when I tried to configure the system. 5 minutes with a screwdriver and the manual sorted it.
Boiler engineer spent quite a few hours messing about with the flue and air inlet pipe, rather than swapping the igniter and fixing the weak spark. Thanks to advice from a PHer, I fixed it.
Sometimes it's just easier to do some research, take advice from someone who knows (there's generally someone on PH who can help), and get stuck in and fix it yourself. Immensely satisfying, too.
Edited by clockworks on Saturday 11th November 18:27
clockworks said:
I just followed the wiring diagrams in the Evohome installation manual that came with the controller. It's available online here: http://www.honeywelluk.com/professional-zone/resou...
GotchyaYup, linked here
On page 42, in the Appendix, is figure 2 which shows an S plan system with 2 two-port valves, setup the way you describe. However, this setup doesn't have any HR92s.
On page 43 is figure 4, which shows a similar stored hot water system, but with zoned heating (with HR92s) setup the way essayer describes.
Not trying to school anyone, just trying to work out the best way to do this
You are right, I never noticed that! I just saw "S plan" and went straight for that method, but with HR92s. Looks like either way is perfectly acceptable then. The only practical difference is that HR92s are optional with the first diagram, but essential on all radiators with the second (any rads without HR92s will get hot in the summer when hot water is called for but the heating is off)
Edited by clockworks on Saturday 11th November 19:10
Edited by clockworks on Saturday 11th November 19:12
Boiler relay advantages:
- gives control over TPI (minimum cycle length / cycles per hour), which otherwise is 1 min / 6 per hour
- lets you keep a radiator running in summer with DHW demand, like an airing cupboard/towel rail
- easily replaced later with Opentherm if you get a boiler that supports it
- no annoying valve noise as the CH valve doesn’t cycle constantly
- means you can use boiler overrun to keep pumping water around the system especially if you don’t have an ABV in the boiler
Main downside
- non standard wiring, might confuse people working on system
- gives control over TPI (minimum cycle length / cycles per hour), which otherwise is 1 min / 6 per hour
- lets you keep a radiator running in summer with DHW demand, like an airing cupboard/towel rail
- easily replaced later with Opentherm if you get a boiler that supports it
- no annoying valve noise as the CH valve doesn’t cycle constantly
- means you can use boiler overrun to keep pumping water around the system especially if you don’t have an ABV in the boiler
Main downside
- non standard wiring, might confuse people working on system
Alucidnation said:
I am still running two V1 Nests but they are a bit redundant now as we have a WC boiler, plus they are very laggy at waking up even after a software update on the 13th October.
If anyone is thinking that they will be replacing their boiler at some point in the near future, i would suggest saving your money on these fancy thermostats and put that towards the WC for the boiler.
Fantastic system and is an immediate saving on your gas usage.
What's a WC boiler?If anyone is thinking that they will be replacing their boiler at some point in the near future, i would suggest saving your money on these fancy thermostats and put that towards the WC for the boiler.
Fantastic system and is an immediate saving on your gas usage.
Edited by Alucidnation on Saturday 11th November 08:15
essayer said:
Boiler relay advantages:
- gives control over TPI (minimum cycle length / cycles per hour), which otherwise is 1 min / 6 per hour
- lets you keep a radiator running in summer with DHW demand, like an airing cupboard/towel rail
- easily replaced later with Opentherm if you get a boiler that supports it
- no annoying valve noise as the CH valve doesn’t cycle constantly
- means you can use boiler overrun to keep pumping water around the system especially if you don’t have an ABV in the boiler
Main downside
- non standard wiring, might confuse people working on system
I’m only justing keeping up with the chat on the last two pages! - gives control over TPI (minimum cycle length / cycles per hour), which otherwise is 1 min / 6 per hour
- lets you keep a radiator running in summer with DHW demand, like an airing cupboard/towel rail
- easily replaced later with Opentherm if you get a boiler that supports it
- no annoying valve noise as the CH valve doesn’t cycle constantly
- means you can use boiler overrun to keep pumping water around the system especially if you don’t have an ABV in the boiler
Main downside
- non standard wiring, might confuse people working on system
Layman question; is it not less efficient having hot water flowing around the pipework (cooling down) and only stopping at the rads, more efficient to stop before it enters the rad loop?
I've wondered how all that works too. On mine it is an S-plan, so if both sides are closed the hot water runs through a bypass valve and a short loop of pipe back to the boiler during the cooldown period. We've recently added a smarter thermostat that uses TPI (Time Proportional Integral).The room stat calls for heat, the CH valve opens and tells the boiler to fire. Water is heated, then the controller tells the valve to close. The hot water then circulates in the short loop to cool down, and this happens over and over again. Unfortunately this loop is just round the boiler, so it heats the garage.
I'm beginning to think this was a blunder.
I'm beginning to think this was a blunder.
My gosh evohome is good....as others have said....it just works!
Not sure on efficiency yet as we've had a cold snap, but we still seem to be on target for £65 pcm gas and electric.
Went round the rads (all oversized double panel convectors) and balanced them up for good measure, seeing a 15-19c drop on the larger ones, flow temp with the vokera in "Sara" zone at load is around 60 with a return of around 38c, must be the bigger rads shedding the heat to return so cold.
Not much more i can do now really, other than let it do it's thing.
Thank God I ditched the wiser system lol
Not sure on efficiency yet as we've had a cold snap, but we still seem to be on target for £65 pcm gas and electric.
Went round the rads (all oversized double panel convectors) and balanced them up for good measure, seeing a 15-19c drop on the larger ones, flow temp with the vokera in "Sara" zone at load is around 60 with a return of around 38c, must be the bigger rads shedding the heat to return so cold.
Not much more i can do now really, other than let it do it's thing.
Thank God I ditched the wiser system lol
Edited by shady lee on Monday 13th November 18:36
Glad it's worked for you!
Interestingly my Drayton system has been faultless now for a couple of weeks and seems to be bedding in now after fiddling with it every other day at the start.
I'm still messing with schedules and adapting these to our lives, when we go to bed etc but all good so far!
Interestingly my Drayton system has been faultless now for a couple of weeks and seems to be bedding in now after fiddling with it every other day at the start.
I'm still messing with schedules and adapting these to our lives, when we go to bed etc but all good so far!
Uncool said:
One last question for the thread - what radiator thermometer/kit are you using to balance the rads properly? An infrared one or maybe something with two sensors (one for the feed pipe, one for the return)?
Working for a air conditioning company I borrowed a Pullman thermometer,rather accurate.
I have just pledged on this, thought it looked good for the money!
Novo - the smartest radiator valve
https://www.kickstarter.com/projects/313176179/nov...
Novo - the smartest radiator valve
https://www.kickstarter.com/projects/313176179/nov...
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