Combination boilers - how do they work?

[tarannau]

Minnie, I can just about take your meagre efforts at trying to figure out Excel, but surely you can figure out a blinking heating programme.

It's a wonder that you can use the bus and those newfangled Oystercard things.

 

[berniedicters]

It will still use a tiny amount of gas for the pilot light. Looking at the sizes of the flames, I'd say you'd need to be away about 3 years to run up one at-home-day's hot water bill.

Typically cited as about £45-50 a year. Some modern boilers don't have a pilot light, but seem to light the gas each time they get a heat demand.

 

[se5]

Get the people who fit the heating to show you how to operate the heating and the system generally - that way you will be able to fully use the applicance.

 

[Minnie_the_Minx]

I think the confusion is over the term "turn off".

The boiler feeds some room heating, yes? You have a thermostat, yes? When you go away, just turn the thermostat down to 5 degrees. The heating is "off".

Make sure no taps are running. The hot water is "off".

It will still use a tiny amount of gas for the pilot light. Looking at the sizes of the flames, I'd say you'd need to be away about 3 years to run up one at-home-day's hot water bill.

Your home will not blow up because of the pilot light. If it goes out, the gas turns off automatically.

If you did turn the gas off at the mains - so the pilot light was off - you would find that it's a pain to re-light the pilot light. This is because you have to overcome the safety cut-out - convince the pilot light it's lit before you can light it!

Yes, with my b/f's system, he has an ON/OFF switch to the boiler. He tpresses it to "ON" and the pilot light comes on and starts heating water. We leave it on for howecver long and then just switch it off and the pilot light disappears. We don't use the thermostats or timers.

Nothing is installed yet. That's happening next week. I will not be using the heating for a while as it's not needed yet, and besides, I have a gas fire in living room.

 

[berniedicters]

I'll probably have the central heating system permanently off, I've never figured out how to work those timer things.

My b/f's heating is on all the time if his radiator is switched on and the water's switched on. Once you switch the water off, the heating goes off, which sounds to me to be nice and simple

Then I suggest investing in lots of warm clothing. Have a friend show you how to operate zips, buttons, etc.

 

[se5]

Nothing is installed yet. That's happening next week. I will not be using the heating for a while as it's not needed yet, and besides, I have a gas fire in living room.

Central heating will use far less gas than a gas fire as it is more efficient. And dont worry about the pilot light - our system doesnt seem to have one, I'm fairly sure the spark to light is produced by an electic sparker internally so yes it does use a very very small amount of electricity

 

[Minnie_the_Minx]

Minnie, I can just about take your meagre efforts at trying to figure out Excel, but surely you can figure out a blinking heating programme.

It's a wonder that you can use the bus and those newfangled Oystercard things.

I have Economy 7. It's crap so I never used it. When I did, I could never figure out how to make the storage heaters work properly so just gave up.

As for using thermostats, most gas engineers who come to my b/f's property see the thermostat and look quizzically at it for some strange reason. There's also no point in b/f using timers as he's up all different hours of the day.

And I don't think there's anything wrong with not knowing how these systems work when you've had a system for 25 years that takes an hour to heat water and you don't have central heating.

If fuel was cheap, I'd just leave it on all the time 'til I figured out how it worked. However, on my wages, I can't afford that luxury

 

[Minnie_the_Minx]

Central heating will use far less gas than a gas fire as it is more efficient. And dont worry about the pilot light - our system doesnt seem to have one, I'm fairly sure the spark to light is produced by an electic sparker internally so yes it does use a very very small amount of electricity

oh right, never thought of that. Will have to make sure my electric key doesn't run out then

 

[ViolentPanda]

No we never switch it off and no the gas bill isn't particularly high.

We had a combi installed about 18 months ago, and have noticed savings of about £60-80 a year, just for our one-bedroom flat, over our old boiler.

 

[Minnie_the_Minx]

We had a combi installed about 18 months ago, and have noticed savings of about £60-80 a year, just for our one-bedroom flat, over our old boiler.

er, are you sure it's not because the price of gas went down?

 

[WouldBe]

It will still use a tiny amount of gas for the pilot light. Looking at the sizes of the flames, I'd say you'd need to be away about 3 years to run up one at-home-day's hot water bill.

My old boiler uses 0.4 units of gas per day with just the pilot light on and 1 unit of gas to heat a tank of hot water.

 

[MysteryGuest]

some little men are inside them sitting around smoking*. when you turn on the tap, they all rush over to where the water is coming through and put their lighters on, all at once, and hold them under the water pipe. TRUE.



* - that's the real reason we have to have carbon monoxide alarms - because of the nasty fumes coming off their cigarettes!

 

[Minnie_the_Minx]

some little men are inside them sitting around smoking*. when you turn on the tap, they all rush over to where the water is coming through and put their lighters on, all at once, and hold them under the water pipe. TRUE.



* - that's the real reason we have to have carbon monoxide alarms - because of the nasty fumes coming off their cigarettes!

does that mean I have to give up smoking in my flat?

 

[MysteryGuest]

yes.

 

[mentalchik]

My combi has a button for hot water and one for central heating........the heating has been off more or less since March, the hot water button is on but the boiler only fire up when you switch on a hot tap......


I've never switched it off completely !

 

[Wilf]

As well as being a bit cheaper to run, I don't think there's many non-combis left now anyway. Re cost though, you do have to watch the water temperature. You get tempted at first to set it as high as the first bit that came out of the tap when you were running a bath (with a non-combi). Because it all comes out at the temperature, you end up having to put loads of cold in to...> wasted gas and water. Best to set it a bit cooler.

 

[WouldBe]

What I would say to anyone getting a combi in, though, is that if you think you may ever want to use solar heating or anything like that, make sure your setup will allow you to incorporate that - there are now combi boilers specifically designed to work in conjunction with solar hot water systems.

I can't see the point. If there is no method of storing the water that's been heated by the sun then you will only get the benefit of solar heated water while the sun is out which is when most people are also out.

 

[Minnie_the_Minx]

As well as being a bit cheaper to run, I don't think there's many non-combis left now anyway. Re cost though, you do have to watch the water temperature. You get tempted at first to set it as high as the first bit that came out of the tap when you were running a bath (with a non-combi). Because it all comes out at the temperature, you end up having to put loads of cold in to...> wasted gas and water. Best to set it a bit cooler.

Yeah, but it means you put less hot in and more cold, or am I missing something here?

I bet there's loads of non-combi boilers. My b/f's a Lambeth Council tenant and I believe they were all supposed to get new boilers years ago, but due to money going "missing" within Lambeth, that never happened

 

[berniedicters]

I can't see the point. If there is no method of storing the water that's been heated by the sun then you will only get the benefit of solar heated water while the sun is out which is when most people are also out.

You do store the solar heated water. But you have to make sure you have a combi boiler that knows what to do with it - or at least will work efficiently with preheated water.

 

[WouldBe]

You do store the solar heated water. But you have to make sure you have a combi boiler that knows what to do with it - or at least will work efficiently with preheated water.

You sure? That's not how I understood they worked

If you're storing the solar heated water why not just use a non-combi boiler to 'top' up the heat when required? As I understood that combi-boiler were less efficient that non-combi ones.

 

[berniedicters]

You sure? That's not how I understood they worked

If you're storing the solar heated water why not just use a non-combi boiler to 'top' up the heat when required? As I understood that combi-boiler were less efficient that non-combi ones.

It is becoming increasingly hard to get hold of non-combi boilers, and most of the R&D effort seems to be going into making the combi ones more and more efficient - though a lot depends on how you measure efficiency. A non-combi boiler might be more efficient in terms of how much heat it gets into the water vs how much goes up the flue, but if you take into account the efficiency of the whole system - heat loss due to radiation from the stored hot water, for example, I think you'll find the gap narrows a lot.

As you have pointed out, solar heating of water isn't something you can rely on, so you need a heating system that will work when you have no solar heated water. You can achieve that via a variety of means, but one of the most straightforward is to simply use your solar heated water as feed for the combi, enabling it to do less work in heating the water when fed with warmed water, but function normally when there is none. But I'm no expert on the niceties of combined solar/gas water heating systems, so this is mostly commonsense and gentle speculation on my part. You may need to ask your questions of someone a bit more competent in that area than me!

 

[Wilf]

Yeah, but it means you put less hot in and more cold, or am I missing something here?

Wasn't sure I'd got my maths right, even as I typed it. What I meant to say is that if you left the bath hot tap running (with an old fashiled boiler) up to the level you'd want, the water coming out would get progressively colder. Might average out the temp to the point you could get into. If you did the same with a combi, you just have a bath full of very hot water.

 

[ViolentPanda]

er, are you sure it's not because the price of gas went down?

Nope, gas only went down 3-6 months ago, after going up twice since early 2008.

 

[Minnie_the_Minx]

Wasn't sure I'd got my maths right, even as I typed it. What I meant to say is that if you left the bath hot tap running (with an old fashiled boiler) up to the level you'd want, the water coming out would get progressively colder. Might average out the temp to the point you could get into. If you did the same with a combi, you just have a bath full of very hot water.

Not at all, the tank runs out of water before it has the chance to get cold

 

[moose]

The newer condensing ones don't even require a 30 second wait for hot water - it's hot in about 2 seconds because it keeps a 'core' of water hot all the time.

 

[berniedicters]

Not at all, the tank runs out of water before it has the chance to get cold

Er...?

*wonders if he really wants to know any more about MtM's, ah, plumbing arrangements...*

 

[Minnie_the_Minx]

Er...?

*wonders if he really wants to know any more about MtM's, ah, plumbing arrangements...*

Then with my b/f's you have to wait another 20 minutes and with mine (electric) you have to wait another hour

 

[WouldBe]

It is becoming increasingly hard to get hold of non-combi boilers, and most of the R&D effort seems to be going into making the combi ones more and more efficient - though a lot depends on how you measure efficiency. A non-combi boiler might be more efficient in terms of how much heat it gets into the water vs how much goes up the flue, but if you take into account the efficiency of the whole system - heat loss due to radiation from the stored hot water, for example, I think you'll find the gap narrows a lot.

Fair enough.

I'm planning on keeping a tank and getting a heat only boiler. So when I get my wood burner and eventually solar panels I can use any of the 3 sources to heat the water.

 

[berniedicters]

Fair enough.

I'm planning on keeping a tank and getting a heat only boiler. So when I get my wood burner and eventually solar panels I can use any of the 3 sources to heat the water.

Yay. I'd like to put solar panels in here - and we have an ideal south-facing roof. It's just that it's not really worth the investment, given that I can't see us staying here for much more than 5 years at the most...we still need to do something about our horrible, ancient combo boiler, though.