Hi,
Our house is arranged over 3 floors and the current system has a zone valve for each floor, all 22 radiators have manual TRVs. For various reasons the old control system must be replaced (long story). The boiler is a large traditional open flue boiler (not condensing), hot water is an unvented cylinder on a separate time clock.
Right now some rooms remain cold even when the thermostat thinks the house is up to temperature (it's an old stone house with little scope for extra insulation and we're not going to replace any radiators).
The honeywell HR80 wireless radiator TRVs with their CM-Zone or EvoHome controllers looked interesting as an option but fitting one to each radiator in the house would be very expensive, cheapest I found the HR80 is £75 so £1650 for the whole house!
Would extra zoning/room scheduling really save that much extra (enough to justify all the HR80s) over the 3 zone control we currently have? Particularly for the first and second floor which just have bedrooms & bathrooms - individual rooms (eg spare room) that are not in use can already be turned down via their TRV.
Instead I'm considering using either the evotouch or three cm927 programmable stat units to control the 3 heating zones via the exisiting zone valves. If necessary I could still add a couple of HR80s to act as remote sensors in the rooms that don't get hot enough under the current system.
The price breakdown (without HR80s) is as follows:
With EvoHome -
. Right now I think I'd prefer the £200 saving.
I think either upgrade would require a lot of rewiring as they do load compensation where an open zone valve does not always trigger boiler firing, that's controlled by the stat via the boiler relay dependant on how close to the set point it is and how fast the house is loosing heat. Is a direct load compensation like this right for an open flue boiler? The Honeywell pages say the CM927 & evotouch are for any boiler but I read some worrying things about direct load compensation resulting in condensate corroding the heat transfer matrix when used with non condensing boilers. I'd get a gas safe man in to do the install (unfortunately all the domestic installers I've contacted so far have been rubbish at giving advice) but once it's in adding extra wireless TRVS should be a DIY job.
Any comments or suggestions would be much appreciated. Should I be considering any other systems?
kind regards,
Bonaparte
Our house is arranged over 3 floors and the current system has a zone valve for each floor, all 22 radiators have manual TRVs. For various reasons the old control system must be replaced (long story). The boiler is a large traditional open flue boiler (not condensing), hot water is an unvented cylinder on a separate time clock.
Right now some rooms remain cold even when the thermostat thinks the house is up to temperature (it's an old stone house with little scope for extra insulation and we're not going to replace any radiators).
The honeywell HR80 wireless radiator TRVs with their CM-Zone or EvoHome controllers looked interesting as an option but fitting one to each radiator in the house would be very expensive, cheapest I found the HR80 is £75 so £1650 for the whole house!
Would extra zoning/room scheduling really save that much extra (enough to justify all the HR80s) over the 3 zone control we currently have? Particularly for the first and second floor which just have bedrooms & bathrooms - individual rooms (eg spare room) that are not in use can already be turned down via their TRV.
Instead I'm considering using either the evotouch or three cm927 programmable stat units to control the 3 heating zones via the exisiting zone valves. If necessary I could still add a couple of HR80s to act as remote sensors in the rooms that don't get hot enough under the current system.
The price breakdown (without HR80s) is as follows:
With EvoHome -
- evotouch controller with one relay: £251
- another three relays: £60 each
- Two DT92 sensors/setpoint adjusters - £65 each
Total cost £561.
- 3 x CM927 stat & relay packs: £102 each
- One extra relay for boiler control £60
Total cost £366.
. Right now I think I'd prefer the £200 saving.I think either upgrade would require a lot of rewiring as they do load compensation where an open zone valve does not always trigger boiler firing, that's controlled by the stat via the boiler relay dependant on how close to the set point it is and how fast the house is loosing heat. Is a direct load compensation like this right for an open flue boiler? The Honeywell pages say the CM927 & evotouch are for any boiler but I read some worrying things about direct load compensation resulting in condensate corroding the heat transfer matrix when used with non condensing boilers. I'd get a gas safe man in to do the install (unfortunately all the domestic installers I've contacted so far have been rubbish at giving advice) but once it's in adding extra wireless TRVS should be a DIY job.
Any comments or suggestions would be much appreciated. Should I be considering any other systems?
kind regards,
Bonaparte
