Can I use a combi boiler - mixed advice - totally confused !

[hztm2]

Hi, Sorry to waffle but I really would be really grateful for some advice. We have a four bedroom detached house (70's style) with Johnson Starley hot air system. The system works ok but we would like to sell the house in the future and have been told that people want modern heating and not old hot air systems. We are quite happy with the system although it is not as good upstairs with the ceiling vents, it is a little noisy, and we cannot set different times for the heating and water.

I have had a couple of companies in to quote for a new 'modern' system but they have given me conflicting advice. One company told me to go for a combination boiler - I would no longer need the water tank so I could knock the airing cupboard out and have the extra space in the bathroom. Also I would not need any header tanks or modifications to the loft. This all sounds great.

Then British Gas came in and said that a combination boiler would be no good as they are not suitable for this size house. They also said that the new expansion tank systems are not very reliable (not sure what this is about?) and that we should stick with a traditional wet system. They want to put tanks in lofts, increase the size of the water tank, etc. Sounds like hassle.

I read so many probs with wet systems that I am worried about changing the hot air system but I do like the sound of the combination boiler. I am just worried about the pressure at the taps and the conflicting advice.

Again sorry for waffle but thanks for any advice you can offer.

 

[petit_pablo]

A big combi will be ok as long as your mains water supply is up to it. 14l/m would be a nice fora decent 37kw boiler

 

[hztm2]

Thank you very much for the advice. My only worry here is that the mains water pressure is out of my control. I guess it could drop in the future and cause a problem with my system.

Could I ask what sort of system is the most popular. A builder told me he always now fits a high pressure system but that they can be a problem?

 

[JohnD]

I am just a householder, but it appears to me that people have a lot more trouble with Combis than with a boiler plus a cylinder. No doubt this is because they are a lot more complicated. Life expectancy unless you buy a very expensive one seems to be shorter. When your combi breaks down you will be quite desperate because you will have no hot water until it is repaired or replaced (with no cylinder, you can't fall back on an immersion heater). Some professionals will tell you that this isn't important.

The BG man might have been talking about the pressure vessell. Yes, these do sometimes go wrong, and people have trouble with pressure being too low/too high and the boiler refusing to run, or constantly dripping. These problems often crop up on here but I don't know what percentage of users get then per year. I expect you would be quite annoyed if you spent thousands on a new system and then found it did that after a year or two.

Also, if you have two people using taps in different parts of the house at the same time, the water available has to be shared between them, this can lead to shower temperatures fluctuating annoyingly and it can take a long time to fill a bath. If you have two bathrooms in use at the same time it can get very tiresome.

 

[hztm2]

John, thanks very much indeed for the information. You are exactly right - I would hate to spend thousands to get a system with pressure and boiler problems. I am beginning to think that I will stick with the hot air and hope I can see the house in the future.

 

[doitall]

For once the BG man is talking sense.

A heat only boiler will need to be half the size of a combination boiler, so considerable more efficient.

It will also be 10x more reliable with less cheap plastic parts to go wrong.

Whatever you decide you need the mains pressure and flow rate at peak and off peak times.

 

[hztm2]

Many thanks for the advice - exactly what BG said - less problems with traditional arrangement and more efficient. Looking around the forum though it does frighten me all the problems with wet systems. I think I might just stick with the hot air and hope I can still sell the house in the future. It has never broken down in the 10 years we have had the house. Once again, many thanks for all the advice.

 

[doitall]

If you go with the better brands, ATAG, or Broag Avanta you will have few problems.

Personally I would look at the avanta heat only boilers in the 15-18Kw range. If you find an approved installer, they can give you a 5 year warranty.

Do try and avoid BG though as they will be several thousand quid more expensive, and only offer you cheap low market products.