Heating/hot water

[Malotkins]

Hello, does anyone know anything about boilers and programmable timers? I'm having a serious mental block about it. We recently had an unvented cylinder and system boiler fitted and now have a programmalbe timer. Up until now we have been switching the boiler on and off when we need hot water as it seems to be that if we turn the heating temperature dial down on the boiler it also turns the water temperature down. We now have this timer but the instructions don't mention hot water, just heat. Any ideas? Its an RF205 if that helps. TIA.

As soon as the cylinder reaches target temperature, its thermostat will turn the boiler off.

You don't have to time the HW. The unvented cylinder is so well insulated that it does no great harm to have it on all day. There may be an extra cost in gas in the region of a few pence a day if you keep running sinkfuls of water to peel potatoes or wash your feet and the boiler keeps topping it up a gallon at a time.

If you want to, and if you have a timer with an HW setting, you can set it to run for about half an hour before and after your morning and evening shower/bath times. The cylinder is likely to be big enough to hold enough hot water for all other use during the rest of the day.

If you can see any exposed hot pipes between the boiler and the cylinder, lag them with 22mm Climaflex or similar.

best grade

budget grade

your RF205 appears to be a programmable room thermostat, to turn the central heating on and off according to the days, times and room temperatures you have chosen.

It has no effect on the hot water.

Thank you Piglet John. So we just set the temperature we want for the water using the dial on the boiler and the boiler will top the cylinder up as needed? It makes sense now, I think. I worry about excessive heating bills.

no, you set the tap temperature you want on the cylinder (the installer probably already did that) and set the boiler temp to be somewhat higher. Otherwise thermodynamics will prevent the cylinder ever reaching its target temperature and the boiler will keep unsuccessfully trying to warm it.

If you have a thermometer, set the boiler to 70C for a day or two, and test the tapwater temperature.

Keep an eye on your gas meter during summer when you are not using the CH. It might be in the region of 1 cu.m per day (depending how many baths you have) costing about 30p plus standing charge, which should not worry you much.

If you want, you can use the Holiday setting on your programmable room stat to, say, 15C for 99 days, and it will prevent the heating coming on unless the house gets that cold.