I have been asked to advise the trustees of a local community building on reducing energy costs. They spend around £10,000 a year on gas for heating and hot water. Majority is for space heating. Cavity walls appear to be insulated, and there is near 100% new double glazing.

The building has six large rooms, including a '2 storey' hall with stage. Radiators (up to 10 in a room) are supplied by Ideal Concord CX mains gas boiler and nearly all are fitted with individual TRVs. The rads all appear to be on one circuit.

A clear problem is that the TRVs are the only mechanism to control heat to individual rooms, and reportedly they are nearly always turned up to maximum from October to May, regardless of occupancy and outside temperature. Windows are opened by occupants if too hot and can be left open - with rads blasting away - after the meeting / bridge session has finished.

Admittedly the first step is to get the building manager to ...manage the situation better. But to help I was thinking about an arrangement where the rads in each large room are controlled as a zone with a room thermostat linked back to the managers office , so he could set rooms on and off and control the temp. (a room being used by Scouts could tolerate a lower temp than one being used by bridge players). Would a scheme like this make sense, and are wireless-linked zone controls feasible to limit the amount of wiring needed?

Management is needed and your input will be invaluable, go for commission on the savings now!

Change the boiler for two or three new condensing ones.

Fit a draught lobby

Add zones and chronostatic control. or programmable room stats linked to each zone valve.

It might be possible to use radio linked TRV,s to control the rooms.

Hi,
I think where they will take this will depend on whether they want to make a capital spend for boiler etc etc, or if they want to make improvements under ongoing maintenance. Once zoned properly it would (ideally) require a modulating boiler to deal with the variable load. If they have TRVs on all rad i would assume a by pass is fitted (??), so if all zone/rad valves close this would be the same but quicker - boiler would stop firing on high stat temp. Obviously moving to a modulating condensing boiler would help. I assume someone has looked up the boiler mentioned.

Cheers Mike up North

The stats are the easy part. There are plenty of programable wireless room stats that could do the job. However in order to have one room calling for heat and others off the plumbing will need to be partioned into zones. Typically each with a zone valve connected to the room stat/programmer. Find out how easy/hard that will be first as it depends on the pipe layout.

One problem I noticed with a community building is this... People arrive for an activity and if the room is cold they turn up the stat. That's usually a mistake. Turning up the stat does not make a room warm up any quicker. The room is invariably cold because nobody arrived an hour early to turn the heating on. The end result is the stat gets turned up to 28 or something silly and the room reaches 20C just as everyone is leaving. I reckon you should see if there is a way to cure this problem. Perhaps link the heating to the room booking system? eg making a computerised booking also reconfigures the heating so that it's warm by the time the room is needed and goes off before the end of the booking unless there is another one following.

Indeed: had to explain to staff at the school that turning up the TRVs does not heat the room faster, just makes temp overshoot. Maybe you can lock the stat not to go above (say) 22C which reduces any overshoot at least. Maybe have some small radiant IR heaters linked to a separate thermostat and PIR movement detectors that come on when room is <17C and there are people. Shouldn't use much extra juice, may add to comfort and reduce temptation to fiddle with other stats. Indeed, 'setback' stats with PIR detectors may generally be part of solution.

(Yes, I dislike resistive heating, but here is a case where a small amount may pay off, in money and carbon terms.)

Rgds

Damon

Well then a PIR-plus-set-back system that keeps room from dropping below (say) 5C out of hours, 14C in hours, and triggers radiant heaters and/or rads when people are in the room and gets to (say) 20C might work well, and with no visible stats.

Something like this at the most basic (without clock, and thus possibly set to a lower-setback temp therefore):

http://uk.rs-online.com/mobile/p/central-heating-controllers/2982386/

or this:

http://www.dealec.co.uk/acatalog/info-5081.html

Rgds

Damon

Hi

Just to add a bit on the Honeywell - it really is worth a look for your installation. Although say a 4 zone system would cost around £1500 controlling 20 or so radiators given you have a £10000 heating bill there is a lot of scope. You may get payback in a year or less by accurately controlling the temperature in the individual rooms and stopping people meddling with them - there is no need for a plumber or any pipe zoning.

I am controlling 12 radiators in three zones and an underfloor heating system - the manager either programs the controllers or manually sets them. You can select temperature in the rooms in front of the radiator group to .5 of a degree from up to 30 metres away. if the area of room in front of the radiator is not up to the selected temperature the valve signals by wireless to a boiler controller up to 30 metres away and this switches the boiler on - when the temperature is satisfied to that part of the room the signal is dropped and the valve closes. This reduces the heat load and when the room is up to temperature all valves shut and the boiler is switched off. I have found this a substantial heat saving over TRVs and a very stable heat management system in the room. You can have a substantial number of radiators in a specific zone.

I agree that its better to preset or manually control to get the room up to temperature before occupation - once up to temperature keep it on until all occupancy is finished - don't be tempted to switch on and off between sessions.

You could try it in a couple of zones for about £500 and see if it works for you.... I hasten to add I have no connection with Honeywell I am just very pleased with my system which has saved me money and improved control no end.

DaveS