After an advice about the central heating and hot water

[ed.easy]

Hello everyone,

(it's my first post but I was reading posts here for a while now)

The situation:
My wife and I just bough a 3 bedroom semi-detached house. The house has an old back boiler in the living room behind the fire place, cold water tank in the loft and a hot water cylinder in the second bedroom airing cupboard.
We will have solar PV system of 4.06 kW installed next week (my wife an I, we both work from home and use powerful PCs plus other equipment and it uses around 3 kW per hour so solar energy is worth having I think)
The idea of a gas boiler in the living room does not appeal to us at all and also the boiler is rather noisy, I was told that its around 30 years old, so I doubt it is efficient too.

Question:
What could we do with heating and hot water? Should we go with combi boiler and have heating and hot water on demand and get rid of cold and hot water tank/cylinder? or can we re-use the tank/cylinder some how? (we can keep tank/cylinder - space is not an issue for us) can we preheat the water with solar energy to help boiler heat the water easier or something like that?
What would be the most cost effective option?
We have a budged of £5k and could scrape a bit more if needed.

Thank you in advance for your help.

Eddie

 

[bernardgreen]

A heat only boiler replacing your back boiler ( keeping the hot water cylinder ) will provide central heating and hot water "on demand" from the cylinder as you have now.

Combis were designed for use in small houses and flats where there was no space for a hot water cylinder. They are complex with more to go wrong inside the boiler and they may not be as efficient as they appear to be in the marketing material.

 

[Doggit]

So is it just you and the wife; are there kids, or are they planned for the current house. Your starting point is going to be the usage; do you have baths, or short or long showers. What is the water feed into the house; is is good, or does it need upgrading.

If it's just the 2 of you, then you could go for a 30Kw combi, but if the water mains is old and corroded, then it may want upgrading. If there's a lot of you, then a 240ltr unvented cylinder would be better run from a system boiler.

£5K will get you a good system installed, but won't really stretch to a solar system.

 

[ed.easy]

A heat only boiler replacing your back boiler ( keeping the hot water cylinder ) will provide central heating and hot water "on demand" from the cylinder as you have now.

Combis were designed for use in small houses and flats where there was no space for a hot water cylinder. They are complex with more to go wrong inside the boiler and they may not be as efficient as they appear to be in the marketing material.

Thank you for your quick reply.

If I have a 10 year warranty for the boiler, most problems would be covered? Another thing I forgot to mention in the bathroom there is an electric shower, would it be still needed if we installed only heating boiler?

 

[ed.easy]

So is it just you and the wife; are there kids, or are they planned for the current house. Your starting point is going to be the usage; do you have baths, or short or long showers. What is the water feed into the house; is is good, or does it need upgrading.

If it's just the 2 of you, then you could go for a 30Kw combi, but if the water mains is old and corroded, then it may want upgrading. If there's a lot of you, then a 240ltr unvented cylinder would be better run from a system boiler.

£5K will get you a good system installed, but won't really stretch to a solar system.

Thank you for your quick reply.

It's three of us, my wife, me and our toddler. There is one bathroom with electric shower (which we don't like) over it. Bathroom is on the first floor above kitchen. The house was built in 70s and it's in a town, water supply seems to be ok.
I am sorry I don't have the right knowledge - what is system boiler and what is unvented cylinder?

 

[bernardgreen]

Another thing I forgot to mention in the bathroom there is an electric shower, would it be still needed if we installed only heating boiler?

Probably not as the cylinder would ( if large enough ) provide all the hot water needed. Minor disadvantage is the cylinder has to be heated before the shower is used. But with a time clock to activate the boiler to heat the water this is not a big disadvantage.

 

[ed.easy]

Probably not as the cylinder would ( if large enough ) provide all the hot water needed. Minor disadvantage is the cylinder has to be heated before the shower is used. But with a time clock to activate the boiler to heat the water this is not a big disadvantage.

The cylinder we have at the moment is also very old, I think is 150-160l so I assume this one would also needs upgrading.

So would it be possible to have heating only boiler and hot water cylinder in the loft? and get rid of cold water tank? Also how hot water cylinder would be heated, gas or electricity?

( I am sorry it might be a stupid question but I have no knowledge about central heating or hot water boilers. )

 

[Doggit]

An unvented cylinder is heated by the boiler, but doesn't use a water tank in the loft. It's fed from the mains wate pressure, so you get a good shower. Assuming the current pipework is okay, then you'd change to a system boiler that gets rid of the header tank in the loft, and provides both heating and hot water. An unvented cylinder can go in the loft, assuming you've got the space up there etc for it, or it would replace the current hot water tank. With just the 3 of you, and only showers, you may get away with a 180L tank.

Check the internet, and you'll pick up all the info you need.

 

[ed.easy]

An unvented cylinder is heated by the boiler, but doesn't use a water tank in the loft. It's fed from the mains wate pressure, so you get a good shower. Assuming the current pipework is okay, then you'd change to a system boiler that gets rid of the header tank in the loft, and provides both heating and hot water. An unvented cylinder can go in the loft, assuming you've got the space up there etc for it, or it would replace the current hot water tank. With just the 3 of you, and only showers, you may get away with a 180L tank.

Check the internet, and you'll pick up all the info you need.

Thank you for your reply.

I've done some reading on the internet and I am a bit confused.
It's only three of us and, one bathroom, one kitchen. Having a system boiler and an unvented cylinder I would have two things which could go wrong and having only a combi boiler then it's only one thing. Am I missing something here? would having system boiler and unvedted cylinder be more cost effective to run it?

 

[bernardgreen]

and having only a combi boiler then it's only one thing

It is only one "box on the wall" but that box has many components crammed into it making service of it more complicated ( and expensive ? ) than a system boiler.

cold water tank in the loft

can feed a vented cylinder which does not have to have the pressure relief valve(s) and other safety considerations that an un-vented cylinder has to have.

 

[ed.easy]

It is only one "box on the wall" but that box has many components crammed into it making service of it more complicated ( and expensive ? ) than a system boiler.



can feed a vented cylinder which does not have to have the pressure relief valve(s) and other safety considerations that an un-vented cylinder has to have.

Thank you for your reply.

But if I have a new combi with 10 year warranty, what is so expensive? I understand that any boiler has to be serviced yearly and it does not matter if its combi or heating only? Does servicing heating only boiler is significantly less then combi? or am I wrong here?
plus having combi I wouldn't have to worry about any water tanks/cylinders, we don't have a problem with them taking up space because we have enough space, but wouldn't it be just another thing(s) that could go wrong some time in the future?

 

[bernardgreen]

But if I have a new combi with 10 year warranty,

A warranty can become invalid for many reasons. Fit a new boiler to existing pipework without giving the system, (radiators and pipework) a complete wash out ( a power flush ) and then the manufacturer may not provide a warranty.

wouldn't have to worry about any water tanks/cylinders,

There is very little to go wrong with a tank and a vented cylinder.

Combi boilers were "invented" to provide hot water and heating in buildings where there was no space for tanks and/or cylinders.

 

[ed.easy]

A warranty can become invalid for many reasons. Fit a new boiler to existing pipework without giving the system, (radiators and pipework) a complete wash out ( a power flush ) and then the manufacturer may not provide a warranty.


There is very little to go wrong with a tank and a vented cylinder.

Combi boilers were "invented" to provide hot water and heating in buildings where there was no space for tanks and/or cylinders.

Thank you again for your reply.

I find that your comments are all very valid reasons. I am a lot confused too and I will definitely think and research more before going ahead and doing anything.

 

[Doggit]

A combi boiler is a very neat and easy solution for providing hot water and heating, but it has a limited flow of hot water. Now that's fine when filling a bath, but a shower needs a higher flow ate to give you a good shower, so you then need a larger combi boiler. And if you're cold water supply isn't sufficient, then when you flush the toilet, the shower may react adversly.

You would need both boiler and the unvented cylinder serviced each year, but an unvented cylinder can then supply a much higher flow rate of hot water.

As always, it's a case of pays your money, and takes your choice. But do a bit more research, and then come back for some more advice.