Combi boiler?

laurel7172

Just had a plumber around to quote for a new boiler.

I *thought* they were all combis these days, but he wants to fit a regular boiler, as I already have a hot water tank and all the paraphernalia.

There are only three of us in a four bed house (and one will be off to uni in a couple of years), so I was thinking a combi would be a cheaper option to run than the traditional "heat up water for five in case you need it" setup, especially as washing machines and dishwashers have become cold fill since the size of the tank was set.

I've had a combi before, so I know about the time lag etc. But in a more-than-one-bathroom property, apparently combis can struggle with the flow rate?

Anyway, he's going to quote me for both. Anyone: any opinions, please?

keystone

4 bed house = conventional installation or unvented cylinder IMHO. See what he quotes. Get more quotes for comparison purposes.

Cheers

Canucklehead

laurel7172 wrote: »

Just had a plumber around to quote for a new boiler.

I *thought* they were all combis these days, but he wants to fit a regular boiler, as I already have a hot water tank and all the paraphernalia.

There are only three of us in a four bed house (and one will be off to uni in a couple of years), so I was thinking a combi would be a cheaper option to run than the traditional "heat up water for five in case you need it" setup, especially as washing machines and dishwashers have become cold fill since the size of the tank was set.

I've had a combi before, so I know about the time lag etc. But in a more-than-one-bathroom property, apparently combis can struggle with the flow rate?

Anyway, he's going to quote me for both. Anyone: any opinions, please?

Good morning: is your current boiler beyond economical repair? Lots of useful info here on choosing a new CH system/boiler.

HTH

Canucklehead

laurel7172

Yes, thank you, the boiler is beyond economic repair.

It seems to be a bit of an underoccupancy issue: buying a boiler that meets our needs as they stand would probably cause problems if the house was fully occupied. And it's a lot more expensive to put a tank in than rip one out. But given that I expect I'll be here (and in five years, alone) for the life of the boiler, as long as the house is warm and there's hot water for two, I'm not sure how much gas I want to burn for the sake of theoretical future purchasers.

When the plumbers (I have another couple of guys coming around later) get back to me with their quotes, how would you recommend I calculate a ball park figure for gas usage for the different boilers? Based on, say, an hour in the morning and an hour at night on the timer? Thank you.

samtheman1k

the capacity is only an issue if you want two or more showers/baths at the same time.

garethgas

My 25 yr old boiler had never been off in its life (except for servicing). All through the summer, water was on 24/7 gas bill = £66 based on actual reading not estimated. And that wasn't even a condensing boiler.
I changed it for a heat only boiler (as your man suggested) recently as it was a direct replacement with little or no alterations.
Opinions will differ but mine is to stick with a heat only boiler, they're more reliable, and you don't HAVE to heat a full cylinder if you don't really want to, although I do.

abankerbutnotafatcat

garethgas wrote: »

Opinions will differ but mine is to stick with a heat only boiler, .

What do you mean by a heat only boiler?

I have read on another post that you can have a combi boiler in a 2 bathroom property if there is an electric shower in one of the bathrooms - is this a good solution?

Canucklehead

laurel7172 wrote: »

Yes, thank you, the boiler is beyond economic repair.

It seems to be a bit of an underoccupancy issue: buying a boiler that meets our needs as they stand would probably cause problems if the house was fully occupied. And it's a lot more expensive to put a tank in than rip one out. But given that I expect I'll be here (and in five years, alone) for the life of the boiler, as long as the house is warm and there's hot water for two, I'm not sure how much gas I want to burn for the sake of theoretical future purchasers.

When the plumbers (I have another couple of guys coming around later) get back to me with their quotes, how would you recommend I calculate a ball park figure for gas usage for the different boilers? Based on, say, an hour in the morning and an hour at night on the timer? Thank you.

Hi...gas usage would be determined by your property's thermal characteristics, whether you have a Part L HW cylinder (assuming a open vented or system boiler), TRVs, programmable room stat, amount of HW you use etc : keep in mind a 30 kw combi will be burn less gas then a 35 kW combi.

Most of my OH's customers request combis (requirements discussed first, mains pressure and flow rates measured) but not all end up with them.;) We have a combi in our own home but would fit a system boiler with an unvented cylinder in our next property (or a biomass boiler if suitable) if we had more than one bathroom.

HTH

Canucklehead

garethgas

abankerbutnotafatcat wrote: »

What do you mean by a heat only boiler?

I have read on another post that you can have a combi boiler in a 2 bathroom property if there is an electric shower in one of the bathrooms - is this a good solution?

You can have whatever you want, either will work but they have 'different' performances.
A typical combi will burn about 28kW in an hour to give you constant hot water. I've no idea why anyone would want that but as I say, opinions will differ. So its pretty much flat out while the tap is open.
A typical system boiler (with cylinder/tanks etc) will burn a max of 18kW (usually a lot less as they modulate down to about 6kW) but will heat a cylinder that you may/may not use up. But then it will only top up what you use.
Theres also the question of reliability. My view is that combi's are considerably more troublesome.
To be honest, its beyond me to explain in a concise way on here as by keeping it simple I'll omit some other properties of each. Suffice to say its a bit like the hare and the tortoise.
I hope I haven't muddied the water for you.

abankerbutnotafatcat

garethgas wrote: »

You can have whatever you want, either will work but they have 'different' performances.
A typical combi will burn about 28kW in an hour to give you constant hot water. I've no idea why anyone would want that but as I say, opinions will differ. So its pretty much flat out while the tap is open.
A typical system boiler (with cylinder/tanks etc) will burn a max of 18kW (usually a lot less as they modulate down to about 6kW) but will heat a cylinder that you may/may not use up. But then it will only top up what you use.
Theres also the question of reliability. My view is that combi's are considerably more troublesome.
To be honest, its beyond me to explain in a concise way on here as by keeping it simple I'll omit some other properties of each. Suffice to say its a bit like the hare and the tortoise.
I hope I haven't muddied the water for you.

Thanks, garethgas. I was hijacking OPs thread anyway. I was just interested in the discussion as we have a combi boiler and would like to add a second shower to the house.

garethgas

abankerbutnotafatcat wrote: »

Thanks, garethgas. I was hijacking OPs thread anyway. I was just interested in the discussion as we have a combi boiler and would like to add a second shower to the house.

One of the things with combi's is their limited performance. Most will struggle with 2 showers.
Then again, if you only use one at a time its not really a problem.