Replacing a standard boiler with a combi - a good idea?

[fatty]

My current CH-HW system is 10 years old. The boiler works fine but the pipes and radiators are full of muck. The boiler is in a daft place in the kitchen (soon to be refitted), occupying much needed wall space. The house is a 3 bed semi with 10 radiators, 1 bath, 2 showers, 4 sinks with HW taps and a HW cylinder.

1) I'm thinking about replacing it with a combi to free up a bit more space (i.e. cylinder and tanks). I've heard some negative reports about combis e.g. taking ages to fill baths, showers not working well (my showers are not powered in any way), reliability concerns ... Should I be concerned about a combi?

2) With a combi, as you are not heating a couple of hundred litres of water for your cylinder, is there a noticeable reduction in gas bills?

3) Is there any reason why a boiler (combi or standard) should not be sited in the loft?

4) How big a job is replacing the boiler with a combi likely to be?

Thanks in advance.

 

[Alfredo]

You have seven Hot Water outlet points. This is too much for a combi. I live in a three bed detached with 9 rads and four Hot Water outlets (inc shower), and the combi is just about perfect for this. Combis are excellent for showers, but will only serve one outlet at a time. I have a Vokera Linea 28 Combi

You should consider a conventional boiler mounted in your airing cuboard and a fast recovery cylinder, but make sure the system is very well flushed first and properly protected with inhibitor

Alfredo

 

[fatty]

Thanks for that. I didn't realise that a combi could feed just one HW outlet. What would happen if (as in my case) all 7 outlets connected to the combi were opened? Would it damage the boiler or just result in low pressure (one seventh of the total) hot water being released?

Thanks for the quick response.

 

[msp]

pressure would drop on outlets and if you was having a shower and somebody else opened a hot water tap, anywhere else in the house, the shower water could get cold. For your house, stay away from a combi.

 

[Paul Barker]

Not being funny when I say when you buy your combi open a savings account so that when it doesn't work you won't have an excuse to come on here asking us to fix it by telepathy just because you have no money.

I haven't got a massive problem with people having combis, but I have a problem with people expecting them to work faultlessly and cost no money over their lifetime. They are going to cost money so put some asside ready.

If you really are poor, and I have been there a few times what you do is you get an open fire and you ask the local merchants to keep their palets for you. They will be delighted someone is prepared to clear them away. Also remember the Yorkshire truism "chop your own wood, you'll warm yourself twice".

 

[Nixt]

Good shout - Paul Barker

 

[Soggy_weetabix]

what about a boilermate or megaflo.

Best of both worlds.

David

 

[Water Systems]

My current CH-HW system is 10 years old. The boiler works fine but the pipes and radiators are full of muck. The boiler is in a daft place in the kitchen (soon to be refitted), occupying much needed wall space. The house is a 3 bed semi with 10 radiators, 1 bath, 2 showers, 4 sinks with HW taps and a HW cylinder.

1) I'm thinking about replacing it with a combi to free up a bit more space (i.e. cylinder and tanks). I've heard some negative reports about combis e.g. taking ages to fill baths, showers not working well (my showers are not powered in any way), reliability concerns ... Should I be concerned about a combi?

2) With a combi, as you are not heating a couple of hundred litres of water for your cylinder, is there a noticeable reduction in gas bills?

3) Is there any reason why a boiler (combi or standard) should not be sited in the loft?

4) How big a job is replacing the boiler with a combi likely to be?

Thanks in advance.

What you need then is high flow combi. The space is worth having as real estateis expensive. Look at how much your hosue is worth and how much floor space the tank and cylinder take up and work out how much it is costing to have water hanging about. It will alarm you.

The Alpha CD50 is a good wall mounted unit that will do you. Or try two cheaper combis.

With a ANY boiler, combi or system, price generally is a good indicator of reliablility. Those in the know, know which are rebadged and sell for less. Glow Worm (Valliant), etc.

 

[Agile]

Dont take much notice of that posting, he is retired and rather out of date.

The normal basic combi gives 8 litres per minute of hot water. Thats enough for one outlet !

The higher power combis give about 10-14 litres. Thats about enough for 1 and a 1/2 taps.

There are a very few specialist combis giving about 14-20 litres per minute and they would feed two taps but are expensive and semi commercial.

Dont be taken in by the storage combis. They store 20-50 litres which have the effect of doubling the flow rate to about 20 li/min but ONLY until the tank is empty !!! Thats about 3-5 minutes in practice.

Their main purpose is to fill a bath in 5-10 minutes rather than 10-15 minutes.

You can still have a cheap 24 kW combi feeding one tap and heating a cylinder as well. Thats a good solution but few installers realise it can be done.

Find a competent CORGI registered installer, ideally a member of the Institute, and take his advice.

Tony Glazier

 

[kevplumb]

You can still have a cheap 24 kW combi feeding one tap and heating a cylinder as well. Thats a good solution but few installers realise it can be done.

it works well 28kw combi feeding kitchen and cylinder on an s plan for the bathroom

 

[pannierstan]

Well said Tony

 

[Alfredo]

I was only trying to keep it simple for the poor guy. Why fit a combi and a cylinder. You may as well fit a C&F Britony for the H.W. if thats the route you are taking.Whats the point when a high recovery cylinder can recover a full cylinder up to temp in well under 15min (some quote as low as 8 minutes, but I'l believe that when I see it.)

I can go with the megaflo, but they aren't cheap and don't last as long as they might given the number of leaking/scaled up ones we pull out round here. You could quite readily use a conventional cylinder to bring cost down a little more, but I hear good things about the high recovery ones.

I quite like my combi, but the additional complication and restricted HW makes the conventional route more sensible IMHO...As for two combis, or a specialist high flow combi...lets keep it in the realm of the realistic for the average person on an average budget shall we.

Alfredo

 

[JohnD]

I like cylinders

 

[Nixt]

Water Systems - you comments are of no use to the OP as clearly from the questions asked is unlikely to be "competent enough". So your suggestion almost seems like encourgement to hire a non CORGI (for reward) which even by your definition is Illegal. As for the banned comment, it is you alone who is attempting to take this into another CORGI debate.

 

[Nixt]

In which case you have no idea either that OP is competent. As for self interest group it clearly does not occur to you that many RGI's might not approve of the current system any more than you do. As for DIY forum I don't see where the OP is asking for advice on how to fit a combi, just on it's suitibility. Which brings to mind your 10l/min comment for basic combi - What sort of bath will that give when the outside main temp plummets in winter?