Combi boiler?

[NotJanine]

Anyone able to give rough estimate of how much to have one installed (smallish 3 bed house, if that's relevant) and remove hot water tank etc. Also, are there any negatives to having them?

[NotJanine]

This is in respect of a house I'm thinking of buying, not current house.

[LifeIsGoodish]

The negative IME is that there can be only one draw on the water at any time. So if you're in the shower (which BTW is a bugger to adjust for temperature) and someone flushes the loo/fills the kettle/starts the washing machine etc, you're in for a nasty shock.

Only way I would have a conmbi would be if I lived alone.

[PigletJohn]

They do go wrong more often than ordinary boilers. When they do, you have no other source of hot water. Some of the parts that are outside a conventional boiler are inside a combi, so need a qualified gas person to replace them, and will be premium-priced branded parts rather than generic pumps, valves and controls.

[BackforGood]

We have electric showers with a combi boiler which gets around the issue of more than one person needing water at once.

[SayrraT]

We've got a combi and we don't have any issuer with using two things at once.

Sometimes OH brushes his teeth while I am in the shower and there is no temperature/pressure change in the shower.

I can't help with the price but when we had ours installed it cost £3500 ish. It is an outside boiler, we have a reasonable size of house (162 sqm) and the boiler is oil fueled.

[Lweji]

The problem with opening two taps at once depends on the boiler, the water pressure at your home and how the pipes are installed.
If you ask someone qualified, they'll tell you what type of boiler you need. Say, if you're likely to have two taps or showers running at the same time, or not.

[Oreocrumbs]

We just switched to a combi boiler and agree I preferred the old boiler, less so when the water tank went wrong and flooded the house mind.

So if the current boiler is still in good order I would keep it going until you come across a problem.

As to price I paid £1800 including labour, can't remember the boiler spec off hand but it's in a good size 4 bed house, oop north.

[Atlas15]

I have one. It has leaked several times. The pressure needs topping up all the time.

[NotJanine]

hmm, interesting

The estate agents I have been viewing with all tell me how good they are.

I have 2 properties I'm considering at the moment -
1 has a combi boiler already
2 has a 16yr old conventional boiler. I was thinking that it could need replacing soon and also it would be handy to get rid of the airing cupboard to free up more space.

[PigletJohn]

a hw cylinder is a wonderful thing.
So is an airing cupboard

If you get more space, you'll only fit it with Stuff.

[PigletJohn]

"fill"

[BackforGood]

I really missed my airing cupboard when we moved here.
To the extent we've tried to recreate it by making a cupboard in an alcove and putting a heater in there when things just won't dry elsewhere.

[concertplayer]

The main advantage of a combi is that it gives instant round the clock
hot water. No waiting for the water to heat. It must save on fuel as it
only heats on demand.
Ours is 6 years old Junior Worcesterbosch. We had 2 quotes ; one for
£2000 the other £3000 (both fully incl) This was to replace an old
Combi in the same position plus wall control thing.
The only thing I do not like is the hot water temp cannot be changed
When the c heating is off in summer you still get really hot water.
You have to warn children guests etc about this

[PigletJohn]

"It must save on fuel as it only heats on demand."

you might think so, but no.

Remember that you are heating a large, uninsulated white radiator on your wall every time you turn a tap on. After it has cooled down, you heat it up again the next time you turn on a tap. Boilers are not efficient when they keep stopping and starting.

"instant round the clock hot water"
You can't get more instant than water that has previously been heated, and is sitting in a well-insulated container ready to be used. By the time a combi has fired up and got itself hot, you could have filled your basin from a cylinder.

[BackforGood]

concertplayer - I can adjust the water temp on my combi.

[Lweji]

Remember that you are heating a large, uninsulated white radiator on your wall every time you turn a tap on. After it has cooled down, you heat it up again the next time you turn on a tap. Boilers are not efficient when they keep stopping and starting.

That is NOT how combi boilers work.
Heating radiators and running water are separate (see link).
If it's heating up the house and you turn the tap off, then it switches to the running water, instead. But, unless you are using hot running water for a long time, the radiator water shouldn't cool too much.

www.explainthatstuff.com/gasboilers.html

[Imnotaslimjim]

Lweji, I think PigletJohn was inferring that the boiler heats in a similar way to a radiator, and the water takes a while to heat before getting to the tap.

I have a combi and hate it. We got it because I love a deep bath and a cylinder never provided enough hot water. However I lose a sink full of water downstairs waiting for hot water to wash up.

[lovelyupnorth]

If your radiators are heating up its not working correctly.

We've had combi boilers in 2 houses over the last 20 years no real problems. Did replace in our current house 3 years ago costs around 2k boiler was £900. That included moving it and installing two extra radiators up north.

We have a 1930s semi with a power shower and second electric shower. Can happily run both showers at the same time.

[Nospringflower]

I loved my combi boiler. Takes up less space, you never run out of hot water and you aren't heating water you don't need.

[Lweji]

With my boiler it's mostly the cold water from the pipes that comes out first. It works the same with the cylinder.
And the cylinder hot water just sits there cooling off.
It certainly doesn't compare with heating up a radiator or a whole cylinder just to get a few litres of hot water during the day.

[unlucky83]

Having grown up in a household of 6 that kept running out of hot water I loved combi boilers -constant hot water and they are mains pressure so tend to be higher pressure.
However you can now get well insulated unvented (so higher pressure) tanks. And actually I think I would prefer that...
The problem with combis is that it takes time for the boiler to switch on and start heating water - I find this is more of a problem in summer when the heating is off. No point insulating water pipes - even if the water in the pipes is still warm you will get cold water coming through before the heating starts - so if you are trying to eg warm up a bath you will be running cold into it before hot. And you do have to waste a lot of water waiting for it get hot. If you want to give your hands a quick wash you can't unless you use cold water...I was hand washing up and rinsing over the rest of the washing up last night and the water temp swung between unbearably hot and freezing.
I thought this was due to my old combi boiler being on its last legs - but no my less than a year old boiler is same at the moment (heating off). Also have one in another house- newish boiler - same problem (which I thought was due to length of pipe run).
Also how fast you run it and how warm the water is in the mains effects the temperature of the water. So in Winter (water is cold in mains) I found even with a boiler designed for a bigger house - so good flow rate it took 5 -10 mins to fill the bath - I used to put hot in first for DCs as it was luke warm coming out the taps at any speed.
Other points - my new boiler (same location) came in at just over £2k (in Scotland - had a new towel radiator etc too so can't be exact -also I needed a condenser drain put in and it was a bit of a hassle).
Last time I got an expensive Worchester Bosch - this time I got a cheaper Baxi cos it had a long guarantee and I don't see the point of spending a lot when they will be out dated in a couple of years - you won't get 16 years out of a new boiler. (Also the Baxi had a Steel heat exchanger - Worchester Bosch had aluminium - apparently condensate in condenser boilers rots aluminum ).
If you are going from a low pressure tank to mains pressure be aware of the possible increase in water pressure. When I did it the (dodgy DIYer who lived here previously) badly installed plastic pipes all came flying apart...water everywhere , no hot water for days- I needed to get most of the hot water pipes replaced. Also they thought I had an electric shower - when they found out it was attached to the boiler they put do not use tape on it saying it was dangerous - they did a bodge to get round it. Also lots of taps etc are suitable for low pressure - so you'll need to check them out too.

[Sooverthis]

I'd keep the tank, when we swooped to combi in the last house it never gave any savings and I really missed the airing cupboard. New house we've replaced the tank (it feeds off the solar so pretty much free this time of year) and I love it. I'd never have a combi again.

[NotJanine]

hmmm...

The house with conventional boiler is now out of the running as they weren't interested in what I was prepared to offer. So the other has a combi, and another I'm going to view I think also has a combi as I can't see an airing cupboard on the details.

They'll only be 3 of us in the house and only 1 bathroom so hopefully that will be ok.

[Lweji]

In relation to unlucky83's post:

Mixer taps are better for CombiBoilers. Both in the kitchen and the bathroom.

I don't see the problem of starting to run a bath with the cold water from the boiler. Eventually it evens out.
I do the same with filling a sink. Starting with cold, and only running the hot tap, eventually it reaches a warm temperature and no waste.

You should make sure the mains water pressure is the correct for your boiler (it does make a big difference) and where the bathrooms are located.
Then, you usually can adjust the temperature and flow of the hot water coming out of it (it may depend on the model)

If you are already buying a house with one installed, all you need to do is open the taps and check how it works.

[unlucky83]

Lweji it is if you have been in the bath for a while and think it needs warming up a bit ....you actually make it colder before it gets warmer....
When DCs were playing in the bath before washing I'd get it running warm in the bathroom sink before turning the bath taps on to warm up the bath...
Same is true if you want to warm up washing up water ....
We do high mains pressure/flow - we don't have the stopcock fully on and the boiler feed was faffed around with ... (by a plumber)
same with shower - you have to run it get warm so when DDs had very knotty hair I wanted to brush through with conditioner I would stop the water, get them out the shower - do their hair then had to warm it up again before they got back in ...
It is a faff....