Combi boiler NOT recommended-Why?

[davidxm]

I don't like (understand) theCH boiler in my son's house, so I suggested they get British Gas to quote for a new combi (and get rid of header tank etc).

BG say they don't recommend a combi boiler for a family (2 adults 2 young children) because of hot water demand!

I've had a combi for 10-15 years and don't undersatnd this logic. If this is the case then combi's would not be recommended for at least 60-70 of households?
Any ideas?
Regards
Dave

 

[kevplumb]

I've had a combi for 10-15 years and don't undersatnd this logic. If this is the case then combi's would not be recommended for at least 60-70 of households?

yup

well overused more so the smaller ones

a combi is not a one size fits all soloution

usually installed because

its a cheaper option

downside is all your eggs are in one basket

 

[JohnD]

combis are widely recommended because they are relatively quick and easy to install, especially in new builds.

I hesitate to say it is also because they are relatively unreliable, so they generate plenty of repeat business in replacement and repairs. Contributing to this is the fact that some of them are very cheaply made, but also that they all contain a lot more parts and complications than a simple old-fashioned boiler.

however, they can only deliver a limited (not very great) volume of hot water at a time. So although it is enough for a shower, or for washing up, if you try to do both at the same time, you will have poor hot water flow at both outlets, and you may notice the temperature at the shower fluctuating painfully. If you are trying to fill a bath, it will take a long time.

If you have more than one person in the house trying to use hot water at the same time, and especially if you have two bathrooms, the restriction in availability of hot water will be very annoying.

When they go wrong you can expect to lose all heating, and all hot water, in the house. This may take a few days, or a few weeks, to fix. If you have an electric shower, or a cylinder with an immersion heater, then you have a fallback so it is not such a problem.

I am a householder not a professional

 

[D_Hailsham]

I don't like (understand) the CH boiler in my son's house, so I suggested they get British Gas to quote for a new combi (and get rid of header tank etc).

What don't you like/understand about your son's boiler?

Are you paying for the new boiler?

 

[Agile]

I've had a combi for 10-15 years and don't undersatnd this logic. If this is the case then combi's would not be recommended for at least 60-70 of households?
Dave

First the recomendation comes from a gas installer. many of them like a nice simple combi installation which gives them the least problem. That may not be the best option for you!

At least 60-70% of households are now single people or just a couple with no children.

For many of them a combi is fine, and probably the best thing for single people.

For a family with children the situation is completely different and stored water comes into its own.

Tony

 

[Alfredo]

2 Adults 2 Children is pretty well ideal for a combi. Thats what we had in our previous house for ten years. However if you are talking en-suite bathrooms and lots of hot taps etc, then forget a combi. Ours was a three bed detached with three hot taps and a shower all run off the combi. It was excellent.

So much with a combi depends on buying a reasonably decent make, and finding a decent installer who will do the job properly not cheaply. BG will do a good enough job, but will overcharge by about 25% minimum.

For best reliability go for a heat only boiler and Y or S plan with either conventional or unvented cylinder. In a nutshell they cope far better with any muck in the system which is what tends to gum up combis in one way or another over time, even properly inhibited ones.

Alfredo

 

[PEDANTICVINDICTIVEMAN]

If you have decent mains pressure coming in, fit a 30/35Kw combi, it will be fine.

 

[TicklyT]

If the mains water supply pressure and flow aren't up to the job, a combi will be as much use as a chocolate teapot. The cold water storage tank is a useful buffer in such situations.

Anyway, if it aint broke, why fix it?

 

[davidxm]

I don't like (understand) the CH boiler in my son's house, so I suggested they get British Gas to quote for a new combi (and get rid of header tank etc).

What don't you like/understand about your son's boiler?

Are you paying for the new boiler?

I don't understand the flue system which has a 'airbreak' section in the roof space? The flue goes into the roof space, there is a gap, presumably for air intake and then the flue continues up thro the roof. How can that be safe?
Yes I am paying for it!!

 

[davidxm]

Anyway, if it aint broke, why fix it?

Mainly, I would like to get rid of water pipes and tanks in the roof space so as not to have any early morning calls in the middle of winter "there's water running down the walls! As I did last year. Also, there's the worry over the flue system, mentioned in previous post.
Regards
Dave

 

[45yearsagasman]

The flue system you describe is a Vertex flue and is perfectly safe providing the installation regs are followed.

 

[PEDANTICVINDICTIVEMAN]

Sounds a good idea to me, get a decent independent Gas reg guy to have a look for you.

 

[D_Hailsham]

I don't understand the flue system which has a 'airbreak' section in the roof space? The flue goes into the roof space, there is a gap, presumably for air intake and then the flue continues up thro the roof. How can that be safe?

Now you know that this type of flue is perfectly safe, is there any other reason for changing the boiler? If not, leave it where it is until it breaks down and is uneconomical or impossible to repair.

Is the house well insulated - loft, cavity wall, double glazed.? If not, it would be a better investment to put your money into that, though DG is not so cost effective. There are many schemes for low cost or free insulation; check out Energy Savings Trust Grant Search

Yes I am paying for it!!

Lucky son! My dad never did that for me.

 

[Razor900]

The most common vertex type flue we come across nowadays is usually very loosely connected to a Powermax

If it is it's time for a decent combi

 

[mickyg]

wont be a powermax as they use a twin flue. The description is a proper vertex, we have a whole estate of myson economists with em.