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Broken boiler - changing to a combi

(15 Posts)
Moanyoldcow Fri 28-Apr-17 20:42:45

I'd love a bit of advice please. My old conventional boiler has broken for the 2nd time in 2 months so I think it's time for a replacement.

Should I go for a combi? Or replace the conventional.

It's a biggish 3 bed house with one bathroom and a downstairs loo. One shower over the bath.

I keep looking online but there's so much conflicting stuff out there I'd like a few opinions before the engineer comes out tomorrow.

Thanks in advance.

PigletJohn Fri 28-Apr-17 23:17:00

is there a reason why you think a combi would be better?

What colour is your hot-water cylinder?

Fill a bucket at the kitchen sink cold tap. Time it. How many litres per minute does it deliver?

How old is the house?

AlannaOfTrebond Fri 28-Apr-17 23:29:40

I've just changed to a combi this week.

My reason for doing so was due to the cylinder going bang last week and flooding the house. I figured with a 16 year old boiler I'd have to replace that too pretty soon, so might as well bin the tank and change the boiler now.

I've got a 3 bed house with 2 bathrooms (but only 2 of us live here). We chose a Worcester Bosch 36cdi as didn't want a noticeable reduction in water pressure in the shower and it has been fine.

The only thing I hadn't bargained on was having to replace the gas feed to the boiler from a 22mm pipe to a 28mm due to greater demand from the new boiler.

Villagernumber9 Sat 29-Apr-17 00:41:51

Alanna. I don't know why your plumber chose a boiler so big that you needed 28mm piping? A 30kw boiler would have been more than enough for you.
Moany. It is all really down to personal preference. A 30kw combi boiler will heat up 15 large radiators and, depending on how fast your water flows, will heat up the water easily for a bath or a shower without the need to waste heating unused water in a tank.

gettinfedduppathis Sat 29-Apr-17 00:46:13

We loathe our combi. We were told it was more energy-efficient and would save money, but we don't because we waste so much water running the tap and waiting for it to run hot - and no airing cupboard any more, which is really tiresome.

When I win the lottery, the first thing I'm doing is replacing it with a traditional system again.

InfiniteSheldon Sat 29-Apr-17 06:45:09

I swopped to a combi and loathed it now we have moved I have stayed with a traditional system and keep them wherever possible in my btl as well. The combi never lived up to its money saving promise, was as slow as a tank to get hot from the tap and cost a fortune to maintain. My traditional system never broke down I replaced it on a plumbers advice as it was 17 years old wish I'd kicked him out the door. Modern tanks are really well insulated (lagged?). As a plus we run the hot water from excess solar energy so it's basically free hot water from March to October. I will probably never have a combi again.

ihatethecold Sat 29-Apr-17 06:53:24

We have a combi that's 12 years old. It's been fine for us. The hot water comes through quickly and it never runs out.

dudsville Sat 29-Apr-17 07:01:16

I will Def do some research before I replace my old boiler add I'm surprised by the experiences on here and doubt want to fall foul. We've for an old combi. It heats quickly and at the elements go through the airing cupboard keeping that viable.

Moanyoldcow Sat 29-Apr-17 09:32:39

Thanks everyone - much appreciated!

@pigletjohn - the real issue are that the water pressure in the shower is very poor and I read that a combi sorts that without having to have a noisy shower pump.

Our hot water cylinder is in an awkward place and if we got rid of it the space would be useful to knock into my son's bedroom.

But that isn't reason enough to do it.

We've just had it confirmed that our old conventional boiler has died and we need to replace and I want to make the right decision as it's what we have to live with a while.

House was built in the 90s

Water cylinder is yellow

Pressure downstairs from cold tap is pretty fast - half a mop bucket in about 15 seconds or so.

We have 8 radiators but it's a big house for 3 bed - about half as big again as a 'normal' 3 bed - 3 large double bedrooms rather than 2 and a box.

Chippednailvarnishing Sat 29-Apr-17 09:35:40

Had a combination fitted 6 years ago, three story house, 9 radiators, 1 shower, 1 bath, 2 loos. It's been fine, instant hot water, bills seem fair and the house is warm in winter

Whatdoiknow31 Sat 29-Apr-17 09:51:36

Villagenumber I expect Alanas plumber chose the 36cdi due to the increased hot water flow rate as she has two bathrooms and a combination boiler is not normally recommended.

Moanyoldcow combination boilers have their place. But please be aware that your heating and hot water will be pressurised. So if any of your pipework is very old you may get leaks.

Also your existing gravity fed shower will not work with a combination boiler so you will have to have that replaced.

Make sure that whoever quotes checks the imcoming cold mains flow rate as PigletJohn said. They should have a thing called a Weir Cup in order to check it. And also draw their attention to your shower to ensure you don't have any added expense afterwards.

A good make of combination will be reliable (we install a lot of Worcester 30si's, which would be perfect for your size house) but remember if the boiler breaks then you have lost your heating AND hot water. So if you wanted to go down the combi route consider an electric shower, at least then you will be able to get washed if anything happened to the boiler.

AlannaOfTrebond Sat 29-Apr-17 10:35:14

DH and I specified the 36Cdi as it only cost a few hundred more than a 30 or 32 and we didn't want to reduce pressure in the shower and regret it at a later date. 2 Worcester Bosch registered installers agreed with us.

For reference we have a 3 storey house with 15 radiators and 2 bathrooms, ( but don't shower at the same time). Incoming water pressure is 16lpm and a 36Cdi can produce approx 14lpm hot water.

Storage is pretty limited in my house and I have gained a massive cupboard where the tank used to be.

The pipework needed to be upgraded as we also have a gas hob and a gas fire, and whilst a 36 would just about run on 22mm pipe, there wouldn't be enough gas coming in to run the other two appliances at the same time.

Villagernumber9 Sat 29-Apr-17 11:49:20

Moany. A 30kw combi would be more than enough for you and will give you a lot of hot water when you want it.
With any combi boiler though, you can't have a nice shower and run the hot water for washing up or a bath at the same time.
I have recently moved and have a vented cylinder system at the moment and can't wait to change it. I waste a full bowl of water at the kitchen sink, waiting for it to get hot but, with changing to a combi and altering the pipe work slightly, that will all charge.
Alanna. You and your DH made the right choice of boiler for the size of house.

PigletJohn Sat 29-Apr-17 13:32:34

"half a mop bucket in about 15 seconds or so"

we really do need that in litres per minute.

Moanyoldcow Wed 17-May-17 20:09:21

Just an update: just had a 30kw combi fitted - it's phenomenal! I think the shower might blow us out of the bath tub.

We decided on combi as it means we're ready to go into the loft if we need/want to and the flow is great - bath filled up about 3x quicker than normal.

Off to have my first power shower!

Thank you all for your advice and input.

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