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Replace Conventional boiler with Combi?

(28 Posts)
hennaoj Tue 17-Nov-20 19:37:41

Hot water cylinder is gone, big leak. Heating engineer is recommending we change the 30 year conventional boiler to a combi and getting rid of the cylinder. We aren't too sure as its a 4 bed house and we have 3 children. I'm liking the idea of a nice big cupboard where the airing cupboard is but we'd of course lose the warm airing part which is needed with the rubbish heat sensor tumble dryers of today.

OP’s posts: |
Lazypuppy Tue 17-Nov-20 19:40:29

I love my combi, instant hot water for baths and kitchen for dishes is the best!

I always used to forget to put hot water on so could never have baths

AuntieDolly Tue 17-Nov-20 19:48:06

I like the new combi but I really miss my airing cupboard sad

hennaoj Tue 17-Nov-20 21:22:35

Does flushing the loo or running taps cause issues if anyone is having a shower at the same time?

OP’s posts: |
flibbertigibbety Tue 17-Nov-20 21:25:26

We switched to a combi a few months ago, and wish we hadn't. Shower pressure has halved, bath takes forever to fill up, pressure goes whilst showering if someone else uses a tap. Only good thing is getting the space from removing water tank. I wouldn't do it again!

Tyzz Tue 17-Nov-20 21:34:28

I've never heard good things about combis. My mother had no end of problems. We get a lot of power cuts and then you have no hot water as well as no power.

sanityisamyth Tue 17-Nov-20 21:42:56

The only thing I miss about my old house is the combi boiler!! Instant and infinite hot water. Bliss!

Chasingsquirrels Tue 17-Nov-20 21:45:37


Does flushing the loo or running taps cause issues if anyone is having a shower at the same time?

On ours when someone uses water elsewhere there is a pressure drop, both our showers are thermostatic and there is a momentary change in temperature and then they revert to the set temperature.
Our water pressure into the house is very good, so we get good hot water pressure.

My house (4-bed, en suite, main bathroom for comparison) had a combi fitted when it was built in 1999.
I've lived here for 20 years (from 2 adults & no kids, then 2 babies, toddlers etc and now mid-late teens) and don't have a problem with it at all.
Had a new boiler about 6 years ago and replaced with another combi (which is a lot better than the first in terms of output, noticeable on the heating side).

My airing cupboard has a small radiator in it (without a thermostatic valve) so is lovely and warm when the heating is on, but isn't heated at all in summer.

RandomMess Tue 17-Nov-20 21:52:25

@PigletJohn is the poster for impartial advice on whether a combi boiler would work in your home.

We had one in our 3 bed with a thermostatic shower and it was fab.

Now have a much larger home with 3 showers on 3 different floors and was advised to get a new mains supply (larger diameter pipe) and an invented cylinder - tis amazing!

Mindymomo Tue 17-Nov-20 22:03:55

My husband fitted boilers for 30 odd years, he would never have one in our home due to water pressure not as good as conventional boilers and due to there being 4 of us in our house, taps and showers are always on, so we would have issues with supply.

It depends if you are a couple or a family.

Also combi boilers don’t last as long, but can be considerably cheaper.

chukwe Tue 17-Nov-20 22:11:45


Does flushing the loo or running taps cause issues if anyone is having a shower at the same time?

If you've high pressure water, then you wouldn't notice any drop in shower pressure.

Please check your water pressure before you move to combi

kwest Tue 17-Nov-20 22:15:55

Can you have an immersion fitted with a combi so in the event of the boiler not working you can at least still have hot water? That’s one thing I don’t like about combi’s, no boiler, no hot water.

BananaPie Tue 17-Nov-20 22:20:18

I wouldn’t have anything other than a combi. The shower in the guest room is electric and doesn’t run off the boiler, so we have that as a back up, but we’ve never had the combi fail us.

jackstini Tue 17-Nov-20 22:24:30

We swapped to one and would never look back

Airing cupboard is great storage and always have hot water

You need a good enough one for the size of your house though - never scrimp, go for the best you can

jackstini Tue 17-Nov-20 22:25:14

Doh - meant to say, 4 bed detached

CovidiotTwunt Tue 17-Nov-20 22:33:20

I have a combi and an electric shower. Water pressure is high here. I've always had combi so stuck with it.

justasking111 Tue 17-Nov-20 22:35:39

We have a combi. 4 bed house. One shower/bath runs off it. Takes 25 minutes to fill a large D bath so we do not bother with them, but I love the instant hot water no judging when the water on the timer will be hot enough. Two other showers are electric but are only for guests. Our bathroom on the combi is downstairs though which might make a difference the power is fine.

ReadySteadyBed Tue 17-Nov-20 22:35:45

We have a combi, Ideal Logic with the tech. Water pressure is sooo much better now and we get hot water whenever we want. Dishwasher and washing machine make little difference to a shower but sometimes turning the tap on can but we had this with a conventional boiler too.

Flamingolingo Tue 17-Nov-20 22:38:27

If you’re not going to claim the tank space for something else then I would opt for a system boiler with an unvented cylinder, especially if you have multiple bathrooms. Combis can work well, especially when space is at a premium, and they’re probably cheaper than both a new boiler and a new tank, but our unvented cylinder is the bees knees. Seemingly limitless high pressure hot water. But again, like a combi, you need decent water pressure coming in and for us that was a new supply pipe.

Mapletreelane Tue 17-Nov-20 22:41:14

Combi in old house, condensing boiler and hot water tank in this house....would never go back to combi. Always something going wrong as so many moving parts, had so many repairs on it. Was a Worcester Bosch and started going wrong just after 2 year warranty finished. Also couldn't have washing machine on or flush the loo if someone in shower. Modern hot water tanks heat up quickly and keep water warm for ages. And I love the airing cupboard. I think combis are great for flats and small houses but not for family house and usage.

PigletJohn Wed 18-Nov-20 00:42:48

Changing to a combi may be a good choice for the installers wallet.

You say you have four people in your house. I think a cylinder will suit you better. You might like to get a bigger one when you change. A bath uses about 100 litres of water. A modern boiler can heat a modern cylinder in around 30 minutes and is well insulated so it will stay hot for a few days or until you use it up. It will work with your old boiler or a new one.

A combi is ideal for a small home with one person in it. The bigger the home, and the more occupants, the less suitable.

If you have the desire to spend several thousand pounds you could upgrade to an unvented cylinder, but, like a powerful combi, it can only give of its best if you have very good flow of water incoming from the watermain, at least 20 litres per minute. In an older house this may require laying a new pipe which is easier than you think. An unvented cylinder can give unsurpassed hot water.

Many people will say "my new combi is better than my 50 year old cylinder" and make the mistake of thinking that the reason is "combi" and not "new"

A new boiler and cylinder can be even better.

BlenheimOrange Wed 18-Nov-20 07:22:35

We are in process of swapping to a combi inspired by the IL, they have a 36kw one which we found brilliant at doing two simultaneous showers when we visited them. So fingers crossed it works as well for us!

BobsKnobs Wed 18-Nov-20 07:29:24

Our combi has been lovely but although 4 beds there are only 3 of us and we all prefer a shower. The combi has been better, but our old boiler and tank were ancient so not a great comparison.

GiraffeNecked Wed 18-Nov-20 07:32:16

our old 4 bedroom 3 storey house had a brand new combi. Lost hot water in shower if someone filled the kettle or tuned a tap on. The bath took forever to fill.

The water pressure into the house wasn’t great.

Current house, 100 years old, 5 bed, 2 bathroom. we’ve just replaced old very small cylinder with a megaflo. Showers are fantastic, bath fills up really quickly, no issues.

Only one plumber recommended a combi to get us the space back...

But it’s a big house,we think the cylinder was the right way to go.

We lost a little single loo with no handbasin which now has cylinder and airing cupboard.

SlayDuggee Thu 19-Nov-20 06:54:00

I’ve got a combi in my 4 bed semi with 2 adults and 2 kids. I can run the bath, sink taps, washing machine, etc and I don’t notice any difference in water temp or pressure.

The only thing i would say that the bath fills up slightly slower. However, with two kids is it better to have hot water all the time.

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