Combi boilers, CHEAPEST WAY TO USE.

sun69uk

What is the cheapest way for me to use my combi boiler. i have been told 2 different things.

the first person says to leave it on low for 24 hours a day and then the second person says use it 3 times a day for two hours each time at full heat.

what is the cheapest way to use them in the climate of big price increases.

DGJsaver

sun69uk wrote: »

What is the cheapest way for me to use my combi boiler. i have been told 2 different things.

the first person says to leave it on low for 24 hours a day and then the second person says use it 3 times a day for two hours each time at full heat.

what is the cheapest way to use them in the climate of big price increases.

Do you leave your kettle on all day ?

jd87

This is a good question and I hope someone out there has the answer. One tip I can give is that you should wash your hands with cold water. It sounds odd but with good antibacterial handwash it is perfectly fine, and it saves having the boiler come on full just to heat a bit of water for your hands.

DGJsaver

jd87 wrote: »

This is a good question and I hope someone out there has the answer.

A quick search will reveal countless threads on the subject

jd87

DGJsaver wrote: »

A quick search will reveal countless threads on the subject

Nope... lots of combi boiler threads but nothing specifically about the cheapest way to use them. Perhaps you could suggest a few of these countless threads?

1carminestocky

jd87 wrote: »

This is a good question and I hope someone out there has the answer. One tip I can give is that you should wash your hands with cold water. It sounds odd but with good antibacterial handwash it is perfectly fine, and it saves having the boiler come on full just to heat a bit of water for your hands.

Just wash your hands (in cold water if you're happy with that) with an 'ordinary' handwash or even soap. Far cheaper and just as effective. Anti-bacterial handwashes and washing up liquids are a marketing department's 'invention'.

DGJsaver

jd87 wrote: »

Nope... lots of combi boiler threads but nothing specifically about the cheapest way to use them. Perhaps you could suggest a few of these countless threads?

Do it yourself , theres a 8 pager on the subject somewhere

anyway , my answer is already in the thread....

sun69uk

So no one will reply and DGJsaver says hes answered already by asking me if i leave my kettle on all day.

mech_2

sun69uk wrote: »

So no one will reply and DGJsaver says hes answered already by asking me if i leave my kettle on all day.

I'm quite happy to reply. The answer is nobody really knows.

Firstly let me say that a combi boiler is no different to any other gas boiler when it comes to heating the house. Combi boilers are only different in that they heat the hot water as needed, rather than storing hot water in a tank. By this I mean the hot water that comes out of your taps, not the water in the radiators.

Conventional wisdom suggests that it's best not to leave the heating on at night (when you are in bed) and when you are likely to be out of the house (assuming a consistent daily routine). Some people think this is so obvious that they can be rude, but then they probably haven't tried leaving their heating on constantly and measuring the gas consumption.

In practice, at the same thermostat setting the difference is likely to be unmeasurable, given daily fluctuations in weather and hot water usage etc. In theory a timer should save some energy (assuming different patterns of usage don't affect heating system efficiency significantly), but theory doesn't say anything about how much you will save. If it's a small amount it may or may not be worth the effort depending on how expensive your house is to heat and whether you end up compromising on comfort.

In a case where you are comparing a lower thermostat setting when on constant than when switching on and off, all bets are off. No one knows the answer. But some people will still try and make out that you are stupid.

deepindebtor

You want to try and keep a constant temperature, just comfortable or slightly lower while you are out of the house and top up as needed, maybe using the manual overide.

I know from experience that my all concrete house takes at least a day to come up to temperature if its been off.

Your house looses heat, each house is individual in its requirements. So set your temperature to be low and top up as needed. Many can get away with leaving the thing turned off overnight but in winter that may not be acceptable. Its all trial and error and what is acceptable to you. Mine comes on three times a day but if I were to go away I would only have it come on twice and at a much lower temperature just to keep things ticking over.

Most new combi-boilers have anti-freeze technology, i.e. they run for a little while even if you have them set to off, this keeps a little warm water in the pipes so they dont freeze, so its doubtful you would break anything.

The argument to keeping it off all the time your not around may not be a good one as it will probably cost more to burn a lot of fuel to bring the house rapidly back up to temperature upon your return so a slow regular top up might be better. Again all trial and error and you should probably spend more time stopping the heat losses than worrying about the boiler.

mech_2

deepindebtor wrote: »

You want to try and keep a constant temperature, just comfortable or slightly lower while you are out of the house and top up as needed, maybe using the manual overide.

Personally I'm against the idea of "topping up" or manual override because it encourages breaking rules you try to put in place to reduce gas usage. Most people don't understand the relation between the controls and how much gas is burnt. "I can't believe how much gas I've burnt. I only turned it up for half an hour". Yes, but it probably charged the house up with extra heat for hours and hours to come afterwards. Also, turning a room thermostat or TRV up higher doesn't heat the room any faster, but many people think it does. So they turn it up to silly levels when they're cold and then later on the house is too hot. Only the thermostat on the boiler itself can make the house heat up any faster and many people don't even know that one is there. And with a condensing boiler, turning that up higher can hurt efficiency anyway.

I know from experience that my all concrete house takes at least a day to come up to temperature if its been off.

That isn't unusual, but it's probably not relevant. It will take a similar amount of time to cool down too, so on a day-to-day basis it will never cool down entirely anyway.

The key issue here is that extreme followers of either method assume the house cools down to background levels as soon as you leave the house in the morning or go to bed at night. If you believe in timed heating then this is great as you lose no heat when you're not up and around. For believers in leaving the heating on constantly that's bad because they've measured how much gas they used when coming back from a winter holiday, noticed it's astronomical compared to day-to-day usage when on constant and again their view is reinforced.

In reality houses don't cool down or warm up in the timescales heating timers operate in, so the assumptions are naive in both cases. It isn't just laypeople making these assumptions. A professor of physics at Cambridge is just as capable of making this error in my experience.

A house heated constantly does NOT use four times the fuel it would use heated for 6 hours a day. Probably not even 1.2 times if the 6 hours is split between morning and evening. Therefore turning the thermostat down CAN offer similar savings. BUT turning the thermostat down AND using a timer still saves most. The issue then comes down to whether you can tolerate turning the thermostat down further with a more consistently heated house versus timed, and as that's so subjective and probably influenced by factors that vary a great deal from house to house/person to person, it turns out that it's just not possible to give that kind of advice.

Your house looses heat, each house is individual in its requirements. So set your temperature to be low and top up as needed. Many can get away with leaving the thing turned off overnight but in winter that may not be acceptable. Its all trial and error and what is acceptable to you. Mine comes on three times a day but if I were to go away I would only have it come on twice and at a much lower temperature just to keep things ticking over.

Most new combi-boilers have anti-freeze technology, i.e. they run for a little while even if you have them set to off, this keeps a little warm water in the pipes so they dont freeze, so its doubtful you would break anything.

The argument to keeping it off all the time your not around may not be a good one as it will probably cost more to burn a lot of fuel to bring the house rapidly back up to temperature upon your return so a slow regular top up might be better. Again all trial and error and you should probably spend more time stopping the heat losses than worrying about the boiler.

That last point depends on the outlay. Most measures against heat loss require you buy stuff and do things to your house. In comparison, twiddling with controls is quick and costs nothing (and a landlord won't need to be involved either).

Personally I think human behaviour mustn't be ruled out of energy saving. If by wearing warmer clothing you can be comfortable with the thermostat 2 degrees C cooler, you can reduce your gas consumption by something like 20%. And that applies whether or not you have the heating on timed or constant. I'm not sure there is another single energy saving measure that saves as much yet costs so little to do. It should be at the top of any list.