Boilermate 2000 and Evohome

Hi,

We are just about to move into a 10 year old house with a Boilermate 2000. I was wondering if it would be possible to add an Evohome controller system, even if it is just to control the heating. My wife works from home 4 days a week and has no idea how to use a thermostat or to put on a jumper when cold and I want to try to save some money.

I have looked at the wiring diagrams and am not sure if it just requires the roomstat in the hall replacing with the BDR91 wireless receiver. I've asked 3 Evohome installers and have 3 different answers which range from £2,500 to fit £1,200 worth of parts most of which are TRVs! To being told the boilermate is obsolete and they would need to replace it.

Any help would be appreciated. We move in May and will be in the Camberley area.

If it's anything like our BM2000 it will have a simple timeclock on it to control heating periods, there will also be a standard room thermostat somewhere. I replaced the thermostat with a programmable 7 day one and just left the heating timer set to permanently on. The room thermostat then effectively becomes the heating controller.

The BM will (unless otherwise configured) always maintain the store temperature so that it is ready to deliver hot water.

If the BDR91 receiver just switches the heating on and off from instructions from the rest of your system, then yes it should just be a simple swap with your room thermostat.

You can also separately control the hot water as well with a timeclock which will reduce the boiler heating the water at strange times of the day, but you have to bear in mind that the BM will only switch the central heating pump on when the store is hot enough.

Anyway the simple answer to your question is yes

Thanks CactusBob,

What is confusing me is there seems 2 ways to turn on the heating. One via the clock the second via the thermostat. Which one takes priority? Looking at the manual I thought I could remove the thermostat all together and bridge connectors 9 and 11 on the ACB, then replace the clock connections with the BDR91 connecting to connectors 21 and 23.

They are effectively wired in series, so both the timeclock and the roomstat would need to be 'on' in order for the CH pump to run. It is only a single circuit in effect. You can remove the roomstat connection at the ACB (bridge the connections so it is always 'on' then just control with your BDR91 replacing the timeclock.

I wouldn't make any other changes because you still need the ACB to manage the thermal store.

In my system I have the internal timeclock controlling both the HW and the CH. The CH is then switched on and off by the roomstat. This seems to work quite well because I've set it to come on about an hour before there is any heating demand, the boiler can then top up the store (if necessary) ready for when the roomstat calls for heat.

Great idea Bob!

Has this had much an impact on your energy bills?

To be honest I haven't really looked, we've changed a lot of other habits at the same time. It made no sense to me that the boiler was topping up the heat in the store at 2am or midday when there had been no use of the stored water. Without measuring heat loss into the airing cupboard (which is nice and warm) I figured the store couldn't be dropping in temperature enough to warrant it running the boiler for what was probably an hour extra a day (if not more).

The store temperature of ours now is 72 deg. The boiler has been off since 8am where I imagine it would have heated it to its satisfied temp of 76 deg. Apparently it will call for heat at 69 deg. So that's a 4 degree drop in almost 6 hours. I suspect though that if I switch the timer on now it will fire the boiler immediately.

I'm looking at replacing it now, not because I really want to, but because I have solar PV now and no immersion heater to dump excess power into. I love our boilermate, the mains pressure hot water is amazing, and it can manage our heating demand with quite a small boiler. We've had an extension built with underfloor heating and it can still manage with that as well. I just want something more controllable, if I only need to heat the top half of the tank in the summer then that's what I want to do.

Lots of people have gripes with them but we've never had a problem really. I had to replace the boiler pump, probably my fault for running it before the system had been fully refilled, but no other problems.

But for some idea of running costs, in February this year we used around 730kWh of gas, so inc. standing charge it was around £35. That's in a 3 bedroom semi built in 2002, decent windows, good insulation, extension with UFH, for three people only having showers.

It does have relatively high electricity usage though. For instance when I replaced the boiler pump with a newer model Grundfos the previous one used 90W whereas the replacement was 45W. It was the same for the CH pump - I replaced with a smart pump.

Thanks for the advice Bob, I think I have it worked out now :-)