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If you have a new combi boiler in a 4 bed 2 bath house...

(20 Posts)
Coldtoeswarmheart Sun 10-Jan-16 19:37:45

...would you mind telling me how you get on with it?

We need a new boiler, and DH really wants a combi for some reason. We had one in our old house (a Potterton) which was temperamental, so I'm not convinced. But I'm willing to be told that they're better these days....

If it makes any difference we're waiting on a quote for a Baxi platinum HE 33 kw with a 10 year gurantee.


PigletJohn Sun 10-Jan-16 19:43:00

Run your cold kitchen tap (also the utility room and garden cold taps, if you have them) into a bucket, time it to full, calculate how many litres per minute you get.

ChishandFips33 Sun 10-Jan-16 19:45:36

We have a combi (WBosch) and I would love dearly to go back to a system boiler and probably will when we start work on the house
The combi is great for kitchen hot water as it's nearby.
However, for the downstairs loo and the main bathroom it takes forever for hot water to come through.
Topping a bath up has to be done by running the water at the sink first to run off the cold (didn't realise this at first!) This could be more to do with the layout/size of the house though
Running two lots of water together and it struggles

We put the Baxi that you are thinking of in a house we did up - three bedrooms, one bath, downstairs loo and UFH and it was great.
House was more compact and we re-did all the pipe work so could ensure it routed better
I guess it depends :-/

Penfold007 Sun 10-Jan-16 19:50:08

Three bed, bathroom and en-suite shower here with an older combi and it's fine. Parents have just had a super duper new combi boiler installed and it's the bees knees.

PigletJohn Sun 10-Jan-16 21:00:05


If you feel like it, you can add a hot water cylinder as an extra zone to your combi boiler. If you have excellent flow, you could have an unvented cylinder.

Coldtoeswarmheart Sun 10-Jan-16 21:03:29

PigletJohn, it's 12.65 seconds to fill a 2 litre jug, which I make 10.5 litres a minute, I think.

ChishandFips33 Sun 10-Jan-16 21:08:31

That's great to know PigletJohn, thank you. The boiler is fairly new but it's at one end of the house and the bathroom is at the other and it's a pain!

Coldtoeswarmheart Sun 10-Jan-16 21:13:11

And judging from some posts above it's probably relevant to mention that the boiler will be in the garage, and the bathroom and shower room are 1st floor, middle of house.

TotalConfucius Sun 10-Jan-16 21:20:58

But even with thermostatic controls on the showers, won't the shower water die off to a trickle at 7am when both bathrooms are in use and someone is rinsing off their breakfast dishes in the kitchen?

(Says she with gas boiler, plus immersions upstairs and downstairs in her house plus electric thermostatic shower in one of the bathrooms. Slight overdrive.)

DontCallMeBaby Sun 10-Jan-16 21:25:43

We have a four-bed two-bath house and have been told by more than one (knowledgeable) person not to get a combi. I think that's been on the basis of the size of the house, rather than anything more scientific based on our piss-poor water pressure (shower in the en-suite and both hot bath taps run on a separate pump, meanwhile you could die of boredom running hot water for the washing up).

PigletJohn Sun 10-Jan-16 21:28:08


That is rather low for a combi. It will take quite a long time to fill a bath, even longer if somebody else in the house runs a hot, or cold, tap or flushes a WC.

Unless you have a restrictive kitchen tap skewing the measurement, you may like to look at running a new, larger waterpipe out to the pavement. It will usually make an amazing improvement to the flow. This would also solve Confucious' problem.

Whatdoiknow31 Sun 10-Jan-16 21:33:18

Wouldn't recommend a combi in a house with two bathrooms to be honest. Reason being say the Dhw flow rate from the boiler is 12lpm, that will be halved if two showers are going - which would make them pathetic, flow reduced even more if someone turns a hot tap on somewhere else.

The optimum system imo, if you have enough flow rate from mains as Pigletjohn says, is to have a sealed system with a system boiler and an unvented cylinder with balanced hot and colds (that's what we have anyway). Word of warning, it's a separate qualification to fit unvented and they can't be signed off with building control unless installed by qualified engineer. Also personally I would not want a pressurised hot water cylinder installed by someone who was not qualified!

Even if you don't have enough flow rate at mains there's ways of getting round it I.e checking your mains is up to current regs, and or installing an accumulator if you have the space.

Coldtoeswarmheart Sun 10-Jan-16 21:39:23

Hmm. You are telling me what I thought I might hear, to be honest.

We currently have a gravity fed system with a standard hot water cylinder in the airing cupboard, maybe we should go for a like for like replacement, or investigate the unvented system a bit more.

TotalConfucius Sun 10-Jan-16 21:49:01

PigletJohn, you misunderstand me! I have no such problem.
This weirdy-weird house in the middle of nowhere has gas-heated stored hot water supplying upstairs hot water taps to basins and baths. An upstairs immersion supplies the upstairs (pumped) shower and one hot tap in one downstairs bathroom (that bathroom has an electric shower so only uses cold water). A downstairs immersion supplies the kitchen, another downstairs basin tap and another downstairs shower. I could have hot water coming out me ears if I so wished!
There is a £20,000 'rationalisation' planned for this summer which will involve living in a caravan for some weeks.
But I well remember our combi and two bathroom days and the frustrated yells from all corners at the morning peak wash time!

peggyundercrackers Sun 10-Jan-16 22:00:57

We have 4 bed and 2 bathrooms, our plumber would not put 2 showers in which run off the boiler. Instead he told us to put an electric shower in one bathroom and a shower run from the boiler in another. He said he has always done this because of the boiler ever breaks down we can still have hot showers which I would not have thought about.

We have we 42cdi and its ok, never had any issues with it but do have excellent water pressure, in fact we had to put a pressure reducer on the main into the house as we were getting something like 8bar on the main into the house.

PigletJohn Sun 10-Jan-16 23:22:26

I don't think you can beat an unvented cylinder, but you do need excellent flow, and in most houses that means laying a larger supply pipe out to the main under the pavement. If you are lucky you will just need to lift a few floorboards and dig a trench through the front garden, but sometimes it is harder. Flow is not the same as pressure.

With any cylinder, you will (should) have one or two electric immersion heaters in it (pref one at the top and one at the bottom) so you can live a near-normal life when your boiler is out of action. Although immersion heaters are much slower than a modern boiler can heat a cylinder, and cost more to run.

Coldtoeswarmheart Mon 11-Jan-16 06:48:34

Yes, we have an immersion heater in our cylinder now, and I'm reluctant to lose it as we have small children who still need bathing whether the boiler's out or not.

TotalConfucius Mon 11-Jan-16 08:36:46

I also go with always having one electric shower somewhere in the house. Apart from the obvious showering, it means that if the boiler's out, or the kitchen is out of bounds, you can wash up, wash your hands and face, wash clothes.
I always go with a basin next to the electric shower and fit an extra long hose - great for a quick hair wash.
Mind you, living rather isolated as we do gives you something of a prepper mentality - I also have a couple of solar showers stashed in the supplies shed! Our electricity is more risky than the gas which of course means nothing works!

Coldtoeswarmheart Thu 21-Jan-16 19:00:56

Sorry to return to this, but I am still in tense negotiations with DH here and have another question to ask....

Does anyone have any experience of the type of combi boiler which has integral hot water stores, and do they overcome the two outlets open at once problem, effectively?

Coldtoeswarmheart Thu 21-Jan-16 19:21:00

(Assuming we got a bigger supply pipe laid, of course....)

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