Combi boiler advice for 19 rads ?

[pilot1701]

hello
We have a large 4 bed house with 19 radiators of various sizes and one immersion tank fed shower I am thinking of converting the large airing cupboard ( 4x1 meters ) to a on-suite and I would be looking to move or do away with the tank , I am reading in various places that the combi is not going to do it with that many rads , and am wondering if that is true ? and if so does anyone have other suggestions , the on -suite shower will be electric .
thank you in advance
Bryan

 

[Harvest Fields]

Problem is not the radiators mate. It is the hot water demand. You can remove the old airing cupboard and cylinder and fit an unvented cylinder instead. (Garage or loft maybe?)

 

[pilot1701]

Thanks for your reply , plenty of room in the loft , the hot water demand will only be for the main shower , at the moment it is only two of us , but as the oil (perhaps I should have said that in the first post , there is no gas here ) boiler is quite old we need to upgrade that first before moving on to doing the bathroom / on -suite
thank you

 

[Aire]

You'll be fine with a combi, as harvest fields says, rads aren't the issue, hot water demand is, but a high powered combi will cope with the demand from 1 bathroom and an en-suite.

 

[pilot1701]

ok thank you
any combi oil boiler recommendations , make / output etc ?

 

[Aire]

Worcester, Grant, firebird, but I don't have much experience with oil to be honest with you. Some guys on here will be able to recommend better than I can so just hold on till they reply.

 

[Harvest Fields]

You'll be fine with a combi, as harvest fields says, rads aren't the issue, hot water demand is, but a high powered combi will cope with the demand from 1 bathroom and an en-suite.

I wouldn’t fit a combi in a 4 bed and most of the lads on here will probably tell you the same mate.

 

[Aire]

I wouldn’t fit a combi in a 4 bed and most of the lads on here will probably tell you the same mate.

Why? 4 bed has no relevance to the hot water usage.

 

[Harvest Fields]

It does if you extend and add another bathroom. Or end up with 3 kids. You will thank me in the long run. Or try to run a tap and a shower at the same time.

 

[Old Account]

For me it depends only on how many bathrooms and people live in that property

 

[pilot1701]

ok , allow me to expand my details , it's a four bed with just two adults at the moment , so we have one kitchen , one utility , one downstairs bathroom with electric shower , one upstairs bathroom with hot supply from immersion tank shower , the on suite will be a electric shower , whilst I think understand what Harvest is saying , that if the shower is going and someone turns on a hot ? tap it wont be able to cope ? is that right Harvest ?

 

[Aire]

whilst I think understand what Harvest is saying , that if the shower is going and someone turns on a hot ? tap it wont be able to cope ? is that right Harvest ?

That's what he's saying yes and if you installed a 28kw combi which gives you around 11 litres a minute then it would be a problem. But a 35kw firebird enviromax has hot water flow rates over 20 litres a minute which is great. If your going to have 2 electric showers and one fed from the boiler then hot water flow won't be an issue for you.

 

[John.g]

That's what he's saying yes and if you installed a 28kw combi which gives you around 11 litres a minute then it would be a problem. But a 35kw firebird enviromax has hot water flow rates over 20 litres a minute which is great. If your going to have 2 electric showers and one fed from the boiler then hot water flow won't be an issue for you.

Grant do a 36 Kw Combi (also a 26KW), both have a 32 litre hot water store, the 36 kw should give a sustained 15 LPM and more if the stored water is "added on", the 26 Kw should give ~ 11 LPM (more if store is taken into account).
In this part of the world the Grant has a better name than the Firebird but I think Firebird have now addressed most of their problems, the SE Firebird was a outstanding boiler.

 

[SimonG]

Don't fit an oil combi for more than one bathroom.

Hounsfield heat only boiler plus rm unvented cylinder if pressures and flow suffice.

 

[SimonG]

Duplicate

 

[Riley]

That's what he's saying yes and if you installed a 28kw combi which gives you around 11 litres a minute then it would be a problem. But a 35kw firebird enviromax has hot water flow rates over 20 litres a minute which is great. If your going to have 2 electric showers and one fed from the boiler then hot water flow won't be an issue for you.

Assuming the mains is up to it

 

[SimonG]

Oil combis do not give a sustained hot water flow, once the heat store is depleted you are fecked.

 

[Rob Foster]

You state you are off the gas main. Now that rings alarm bells in my experience, often the utility dont supply mains water to outling dwellings at pressure AND volume enough to let your combi do the businss hence some high level stored water for high demand periods is essential esp. in the summer when farmers etc. are sucking the main dry.
Have you tested the pressure and the volume ?
Rob Foster aka centralheatking

 

[king of pipes]

Grant is the most popular brand in our neck of the woods, personally i dont do oil but I have fellow installers I pass jobs onto oil combis seem to cause them more problems than a standard heat only boiler and separate hot water cylinder. Kop

 

[SimonG]

You state you are off the gas main. Now that rings alarm bells in my experience, often the utility dont supply mains water to outling dwellings at pressure AND volume enough to let your combi do the businss hence some high level stored water for high demand periods is essential esp. in the summer when farmers etc. are sucking the main dry.
Have you tested the pressure and the volume ?
Rob Foster aka centralheatking

Load of codswallop.

Just because there's no mains gas doesn't mean there's no decent mains water. Yes there are a few spots off of mains water running on springs or bore holes.

In fact there are a lot of places round our way that are running on mains pressure running at up to 10 bar plus.

 

[Rob Foster]

Load of codswallop.

Just because there's no mains gas doesn't mean there's no decent mains water. Yes there are a few spots off of mains water running on springs or bore holes.

In fact there are a lot of places round our way that are running on mains pressure running at up to 10 bar plus.

So its not worth testing domestic mains water pressure and flow before fitting a highflow combi boiler ? I know parts of London are poor but its a test which should always be applied in my opinion
Rob Foster aka centralheatking

 

[Rob Foster]

Load of codswallop.

Just because there's no mains gas doesn't mean there's no decent mains water. Yes there are a few spots off of mains water running on springs or bore holes.

In fact there are a lot of places round our way that are running on mains pressure running at up to 10 bar plus.

Pressure and volume are almost seperate issues, but inter related in this case...anybody could get 10 bar squirting water thro a 8mm microbore but it wont fill a bath
Rob Foster aka centralheatking

 

[SimonG]

Stop trying to backtrack on your ridiculous comment.

Never mentioned not testing flow and pressures for unvented or high flow combi.

Also didn't say the 10 bar was through an 8 mm pipe.

You've been giving some real crappy info since your reincarnation.

 

[SimonG]

On my ignore list.

 

[Rob Foster]

Stop trying to backtrack on your ridiculous comment.

Never mentioned not testing flow and pressures for unvented or high flow combi.

Also didn't say the 10 bar was through an 8 mm pipe.

You've been giving some real crappy info since your reincarnation.

so never mention not..means you did advise testing hmm ?and you did not suggest 1o bar thro 8mm I agree I used it as an example I agree cool down plse
kind regards Rob Foster have a good weekend ..off to North Cornwall in a min

 

[AWheating]

I'd fit an unvented cylinder myself but the customer is always right if they pay enough and I put it into writing I've advised against it.