Heating Controls Upgrade

[colinm1]

HI folks, here's the scenario:

3 Bed bungalow with converted upstairs containing bedroom/ensuite and office. Rear extension kitchen/living space open plan. Built 2009/2010 and well insulated.

Currently heating has two zones, downstairs and upstairs, with a basic Horsmann timeclock (2 Zones + HW) and TRVs. There is a room stat in the upstairs hall which doesnt seem to do a lot ie I'm not convinced it actually kills the boiler, and in any event someone has parked it directly above a radiator!

Total 14 Rads across what I'd like to become 9 'zones' as the current zoning doesnt do much for us.

Temperature control within the zones is quite important as we have a couple of log burners in different rooms downstairs and we want to make the most of those.

So whats the options?

Cobble together some sort of system from the Conrad Thermostat/Valve actuators and boiler interlock? If thats the way to go, should I keep the time clock on the boiler and install two boiler controllers in series with the output of the current two zones so I can override it to OFF at any time and still keep the DHW timer independant of all this to back up the solar water heating in the summer?

Honeywell Evohome stuff any good? is this a DIY install and do I lose my two zones? I work from home a lot so heating just the upstairs for the office is handy, and with programmable TRVs in the bedroom it shouldnt be getting heat during the day etc.

Pegler i30 valves and the PC control suite/USB stick - does the PC programming simplify setup, and more importantly can it easily reprogramme all valves if i did a mass battery change in the autumn for example? Any options for boiler interlock?

Danfoss Z Wave stuff - looks crazy money and probably too clever for what I want?

Any other suggestions?

One other thing, although I have a zone for DHW, the tank gets heated when any of the boiler zones are being run. Having the solar panel for DHW I'm not sure that is the most efficient - should I be avoiding applying any boiler heat to the tank in the morning to make the most of any sun during the day and leave any water topping up to be done during the boiler's evening heating cycle?

 

[colinm1]

Well after a fair bit of investigation in the wiring centre with a testing screwdriver to see what was going on, and labelling all the connections I managed to work out that most of the wiring and some of the pipework was wrongly installed.

Firstly the room stat wasnt connected to anything other than a permanent live so the LED came on and off giving the impression it was doing something.

Secondly the zone valve for the DHW was installed in the wrong place so that when it closed it also blocked the hot water from the boiler from accessing zone 2 (upstairs rads). It was also quite dangerous as when it was closed it isolated zone 1 from the expansion vessel.

Thirdly the switches in the motorised valves were not calling for heat from the boiler, the three channel timeclock was doing that alone.

It was pointless fixing the room stat as it was in a useless position for both of the zones, so I took it out and installed two CM927 wireless stats to control each heating zone with the zone valves switching the boiler. The two heating zones on the timeclock are now set to on all the time with the timeclock only being used to set the DHW on times. I have just stuck with the TRVs on the rads rather than go to the expense of splitting the two zones into further smaller zones with CM Zone or equivalent.

Then the pipework...I was able to isolate a small section of pipe by closing the two existing motorised valves and the gate valve at the cylinder, and install a further zone vale in the correct place. This now controls the DHW heating with the new valve calling the boiler when both the timeclock and the cylinder stat require it. Space was restricted and I'm not au fait with soldering and bending copper pipes so used plastic pipe and push fit fittings. Having the DHW isolated from the heating circuits is important on this systen as it allows the solar collector to heat the water during the day and then we can top it up when necessary. Finally for simplicity I just left the badly located motorised valve in situ and took the motor off it so that it stays permanently open. Whilst I was there I installed a boost timer beside the tank which overrides the timeclock for 15,30,60 or 120 minutes of hot water only from the boiler. I'll use this in the summer if a check on the cylinder temp shows that the solar panel hasnt heated enough water.

A bit of fag packet calculation estimates that I am currently using around 3 or 4 Litres less oil than before on an average day, and equally as importantly nobody ever feels that they are either warm or cold in the house. The log burner is lit when we're sitting down at the TV to make that room warmer and we find 17.5 ish comfortable everywhere else. The CM927s are set to cycle three times an hour rather than the usual 6 on a gas boiler and they seem to work very well at maintaining a set temp with the rads normally warm rather than either hot or cold.

I was going to install a dedicated boiler relay to synchronise the two CM927s but on consultation with Honeywell they said that the additional boiler relay was only necessary if there were 4 or more zones. Considering that they are about £70 I was happy with that. I have both zones set to come on in the morning at the same time, so in theory the first cycle of the day should be synchronised anyway, and after that the zones are generally working at different times anyway.

The whole lot cost about £250 for the new valve, some fittings and the two Honeywell controllers. If I save only 2 or 3 litres a day for 6 months a year, at 60ppl oil price it should pay back in a year or so.

Finally I toyed with removing the three channel timeclock and replacing with a single channel just for the hot water, but figured for holiday mode only, I can disable all three zones for a set time from one place so i think I'll leave it there.

Last on the list is an SMS controlled heating boost for when someone is coming home early, but havent got to that yet. Its a bit of a gadget and not strictly necessary. I am going to install one in our holiday home first and see how it goes there. There is a UK manufacturer selling these units on ebay for £74 with good feedback.