My family and I just moved into a new home. Our old home had a 'combi boiler' that was similar to living in the US. We turned the thermostat up, it got warmer. We wanted hot water, it provided...
We now live with a boiler (in the kitchen) that has a hot water cistern in the airing cupboard. I believe this is a system boiler. If anyone has answers to these basic questions, please advise!
1) There is a thermostat on the wall, on the cistern, and on the boiler itself. Should the thermostat on the cistern be lower than the thermostat on the boiler itself (not really a thermostat but a scale of 1-6)?
2) The boiler has a switch that can be set to "off", "hot water" and "hot water and heating". We can also set the boiler to "constant", "two times a day", "one time a day" and then set when we want the boiler to come on during the day (e.g., 6-7 AM and 5-6 PM) with the mechanical timer.
3) When we put on the "hot water" switch and it is at 5:05 PM when the boiler is supposed to be heating hot water, why do all the pipes and radiators also feel hot? Does the hot water run through the pipes to reach the cistern?
4) What happens when the hot water in the cistern runs out? If it is 10 AM and we have run out of hot water, do we just have to wait it out or do have to turn it on "constant" and wait a bit until we have some more hot water?
5) Any tips on saving energy/money with these types of boilers?
Thanks!
1) Thermostat on the hot water cylinder should be set to 60 deg C, there isn't really a nominal number for the dial on the boiler - I've dialled mine down until the hot water stops reaching full temperature. That gives the best gas consumption (radiators and hence flue gas will be cooler), but takes a bit of experimenting. The 60 deg C is a regulatory requirement for legionella protection, although so far as I'm aware there has never been a case of legionella infection from domestic hot water.
3) Shouldn't, but it isn't uncommon for the valves to pass water through, or indeed the hot water to circulate backwards through the radiators. In practice there isn't much you can do about this. Best way to check which is going on is to feel the feed and return pipes on the radiators and see if the hottest one is the same when you're doing hot water and when you're doing heating. Either way, thermostatic radiator valves will probably help. That's assuming an S-plan system. Others have already mentioned what to do if it's a Y-plan system.
4) Either works. More modern heating controls (not hard to fit if you're a confident DIYer) will typically also have a "boost" button which turns either hot water or heating on for an extra hour.
5) i) Insulate the hot water cylinder. If the airing cupboard is detectably warmer than the rest of the house, you'll benefit by stuffing some more insulation around it or fitting an insulating jacket.
ii) Thermostatic radiator valves will probably help, they're pretty cheap to buy but I think you've got to drain and refill the heating system to fit them. I like ours a lot, as they keep all the rooms at the right temperature easily.
iii) Turn down the 1-6 dial on the front of the boiler a notch at a time over a few days until you notice the hot water isn't hot enough, then turn it back up a notch. Condensing boilers (basically any boiler under about 10 years old) stop condensing when the water temperature gets above about 60 deg C, so there are some fairly big efficiency gains by turning the water temperature down.
iv) Insulate insulate insulate - the biggest savings will always be from reducing heat losses and hence heating demand. Hot water is typically 10-20% of an annual gas bill.
