Confused!! - Combi or cylinder boiler??

26fin

Hi,

Im really confused and keep getting conflicting advice from plumbers so any extra advice greatly appreciated. Ive no idea about plumbing so apologies if terms may be a bit basic!

We currently have a boiler with a hot water tank and cold water tank in the loft (was already installed when we bought the house). We're currently fitting a new kitchen and the plumber thats doing the work has advised a new boiler (combi), and now is the best time to do it with the old kitchen being ripped out (boiler is in the kitchen).
Whilst the boiler hasnt given us any problems, its got to be a good 15-20 years old so were considering upgrading now, otherwise sods law it will probably pack in 6 months after new kitchen installed!!
Really need help on whether a combi system would be more suitable or keep the current system and just upgrade the boiler?? Some research Ive done seems to suggest a combi isnt suitable for a large house?
Our house has 6 bedrooms, 2 bathrooms (1 is electric shower), 1 ensuite and 1 cloakroom. 12 radiators.

Thanks for any advice

jbworldwide

I'm just about to complete on a new build town house which is over 3 floors and they have not put a combi in becuase they say they are really only suitable for flats or small houses. So I will have a bolier and a hot water tank.

I have also read stuff about combi's being poor in terms of life so I am glad that I dont have one.

26fin

Thanks for the reply.

That seems to be what I have found when Ive tried to research it - just cant understand why a few plumbers have recommended it for our house if this is the case!

So if we just need to upgrade the boiler - should it be a condensing boiler? or is this not relevant with this type of system?
As i said before excuse any stupid questions as whilst I'm trying to research what I can, I'm not very familiar with any plumbing/boiler issues!!

btr30

I think these days you will find difficulty sourcing anything other than a condensing boiler.
My recommedation would be to instal a new system (non combi) boiler with a new unvented Hot Water Cylinder, with imersion heater back up, but this is a "Rolls Royce" system, which will add to the installation cost.
But nothing wrong with keeping the existing cylinder.
The heating circuit with the new boiler will operate at a higher pressure, which may cause issues with any old fittings etc, which may be seeping, but not noticable as expansion tank will continually fill system at present, but this will cause new boiler to shutdown until pressure is topped up.

alleycat`

Has the plumber gone to the trouble of working out your water flow rate before deciding that a Combi is ideal for you?

If you've got inadequate water pressure then a Combi is something to be actively avoided.

Both systems have their positives and negatives but i'd be wary of anyone suggesting you "change" without doing the basics.

26fin

Thank you both for your replies.
I think the existing cylinder has an immersion back up. There is an immersion switch there which we used by mistake when we first moved in!
The pressure to our house is low (just above what welsh water deem acceptable though!) so that definitely makes our decision I guess.
In terms of a new boiler, Ive read that valliant is a good make?
Other option if were not changing to a combi system is to maybe what until the boiler packs in, as Im guessing fitting a new boiler of the same system wouldnt cause too much disruption of the existing pipework. Seems the older boilers seem to have a much longer lifespan than newer boilers!

matelodave

Bear in mind that a new boiler has to be condensing - it's the law and so will need a condensate drain and probably a different flueing arrangement to the one that you've got - most of them seem to have fan assisted flues rather than big square openings.

It's worth making sure that if you do keep the old boiler that it can be replaced fairly easily without dismantling your shiny new kitchen and having to run or modify plumbing behind cupboards - I know I've been there.

Also make sure that any extra wiring that you might need for a new boiler and it's controls is at least run in ready - it's far easier to do now that when the kitchen is completed and decorated

26fin

Ok, thats good to bear in mind - thats my fear!!

Whilst I'm loathed to replace something that seems to be working fine, the last thing we want is it packing up in 6-12mths and the new kitchen pulled apart!

I'll speak to the plumber again about what extra pipework will be needed and if it will be possible without affecting the kitchen.

btr30

The main changes will be: - installation of condensate pipe, which will run to outside, flue, and converting system from tank to mains water (which can be done in the attic).
Shouldn't cause too much disruption later. Also newer boilers tend to have smaller footprint, so you should have same wriggle room if there are problems.

Cardew

btr30 wrote: »

The main changes will be: - installation of condensate pipe, which will run to outside, flue, and converting system from tank to mains water (which can be done in the attic).
Shouldn't cause too much disruption later. Also newer boilers tend to have smaller footprint, so you should have same wriggle room if there are problems.

That is a little confusing.


The main changes for what?? To a Combi? or a like for like replacement boiler? Bear in mind the OP's low water pressure.


Also the condensate pipe does not have to 'run to outside'. Both my boilers(one a combi in an annex) have the condensate running to sink waste pipe. This eliminates the problem of the pipe freezing. Also the condensate can be pumped to a suitable internal drain if necessary.

26fin

Yes Ive checked the dimensions of a new boiler and they're slightly smaller than what weve got, but we are building the boiler housing slightly bigger just in case