New boiler needed - which type?

macman

Because some people want instant hot water, in unlimited amounts-so choose a combi.
Some people want to run a bath and a shower simultaneoulsy, or want an airing cupboard-so choose a conventional boiler.

Aquatronixjenny

A combi boiler is great in a small property or a flat, but may not cope in a large property and will definately struggle if you need to run more than one hot tap at a time. I had a 28kw combi in my 3 bed bungalow and it struggled.

Personally, if your hot water tank is ok I would just go for a replacement heat only or system boiler. Changing to a combi means a lot of messing around with pipe work and removal of tanks. A new immersion tank should only cost you £500 or so, but changing from a regular or system boiler to a combi will be far more expensive.

As for makes, when I install I tend to stick to Worcester Bosch or Vaillant. Never had any problems with these. I would steer clear of Potterton, we get called out to these all the time!

Owain_Moneysaver

If reliability is the prime concern then do not have a combi.

If you keep a hot water cylinder (you may have to have a new cylinder insulated to current Part L standards if you have a new boiler, which will put the price up) then you can have an immersion heater as backup for the hot water and tenants can make do with fan heaters for a few days if the boiler fails in winter.

With a combi boiler you are totally reliant on the boiler for heating and hot water, and tenants will not tolerate no hot water for very long at all.

In terms of efficiency, with a stored hot water system there are small thermal losses from the cylinder, but with a combi you are burning gas every time you turn the hot tap on, and you have to wait for the boiler to heat up even if you only want to wash your hands. (You can get boilers with a pre-heat function but that's the same as storing hot water.)

Combis are really useful in small flats where the cylinder takes up an otherwise useful cupboard.

In houses you can put the boiler, and the cylinder if it's mains pressure, in the loft if you want to save space.

abankerbutnotafatcat

Thank you everyone who has contributed - it's really helped!! Double-thanks to Owain Moneysaver who really addressed my issues.

One thing that has been touched on that I failed to mention is that under the current system there is a shower pump and that would not be possible with a combi although I have no idea as yet what the mains water pressure is.

As Owain points out, having a boiler with water tanks gives the option of having a immersion heater if the boiler breaks down - this is what they are currently using and is invaluable.

Any further thoughts are extremely welcome, particularly any recommendations of particular makes or models or ball park figures of the cost for like-for-like replacement (with the possibility of a new tank as has been mentioned) in central London (zone 2) so that I won't get ripped off too much (i'm seeking 3 quotes but what if they are all trying to rip me off??

Thanks again.

Aquatronixjenny

Agree totally with Owain. He has mentioned all the things I forgot.

We charge around £2k for a heat only boiler installation and that includes a power flush on all rads (which you will need) and the supply of the boiler and all other materials. A new immersion cylinder may set you back around £400 - £500 more, as the c/h system is already drained down they should give you a discount on this installation.

We aren't in London though, but on the Surrey/Hants border which is still fairly expensive. This should give you an idea of the sort of cost you are looking at.

abankerbutnotafatcat

Thanks, Jenny. You're nearly close enough - another few miles up the M3...

Please can you confirm why a new immersion cylinder is needed and why it costs so much. Currently, there's a huge hot water tank in the kitchen. It has an immersion element in it. The element stopped working once so we just took it out and replaced it and it didn't cost much. Is it new safety or energy efficient regulations or is it because the older tank might not be compatible with the new boiler?

macman

A 30 year old hot water tank is probably heavily scaled. A system this old could be not fully pumped, single pipe, who knows? and I doubt that it has modern controls: i.e. TRV's or a decent programmer.
Without knowing exactly what you have at present, it's impossible to recommend.
But if you're going to rent, get it all done in one go beforehand-you can't start messing around changing tanks and pipe runs once the tenants are in there.

heating-eng

gas4you wrote: »

All the boilers I mention are not cheap boilers by any standards.

The Atmos and intergas are excellent boilers and as they have less parts will therefore have less chance of going wrong.

The Sime has the same components as most other boilers, in fact they make their own Giannoni heat exchanger under licence and make the Giannoni for Vaillant as well.

The worst after sales service is without doubt from Vaillant. All those I mention would have any warranty work usually carried out by whoever fitted it and they would or should, carry the spares kit on their van for a first time fix. Depends whether you want to use an installer who is good enough and been trained to be a service engineer for your particular boiler, or use someone who just installs and doesn't know how to fix them.

If you have to replace the cylinder, then if you had a new standard heat only boiler this would cause the work to be more expensive as compared to a new combi being fitted.

So they don't have there own engineers to repair these boilers then?
I wouldn't want to get involved with a company that do not employ direct labour to repair ther boilers.

Owain_Moneysaver

abankerbutnotafatcat wrote: »

Please can you confirm why a new immersion cylinder is needed and why it costs so much. Currently, there's a huge hot water tank in the kitchen. It has an immersion element in it. The element stopped working once so we just took it out and replaced it and it didn't cost much. Is it new safety or energy efficient regulations or is it because the older tank might not be compatible with the new boiler?

New energy efficiency regulations (Part L of the building regulations). Your existing cylinder may already be compliant.

Modern cylinders with high recovery coils will heat up much more quickly too, so once someone's had a bath there won't be an hour's wait for the cylinder to heat up again.

heating-eng

Owain_Moneysaver wrote: »

New energy efficiency regulations (Part L of the building regulations). Your existing cylinder may already be compliant.

Modern cylinders with high recovery coils will heat up much more quickly too, so once someone's had a bath there won't be an hour's wait for the cylinder to heat up again.

Please don't mis quote and mislead people.
You would not normally need to update the cylinder, you may wish to but it is not normally required.
Also part L is not new.