Heating Design Advice: Combination or Separate

[hashmio]

Hi guys

I recently purchased a new house and it requires a completely new heating and hot water system.

I am deliberating on whether to go for a combi boiler or just keep the heating and hot water separate. I was wandering if someone could advise. As most people I am on a budget but if the cost difference in energy savings and maintenance costs can be recouped over 3-5 years I would be willing to go for the more expensive option. I have been told that combi boilers are very complicated and the maintenance cost are higher then a separate system.

I have attached the floor plan of my house and here some additional details which maybe useful when offering advise:
Victorian Semi
Ceilings around 2.6m high
no basement
2 bathrooms with shower
3 young children

Feel free to ask me any relevant questions

Thanks

Os

Untitled

• hashmio
• 22 Oct 2013
• 1

 

[Agile]

There are so many other questions like how many occupants and if they like baths or showers.

Far better to get locals to come and quote although my advice is to pay somebody to advise you and then get quotes based on that spec.

I don't think you will get the best advice from anyone coming to give a quote for free.

Why should they waste their time giving you all the advantage of their skills when all you want is the cheapest east Europeans to do the work.

Tony

 

[Galoka]

Having had both a conventional stored HW system, then a combi ,in the old house and now in this house a conventional stored system again I can't say I think that the differing maintenance costs are are an issue really. Yeah, combis are a bit more complicated, but then modern boilers anyway are more complicated in general. I think having the right system for you is much more important - otherwise it could just be a frustration in the future.

Running costs? theoretically a combi can be cheaper as it is only heating water when it is needed, tho much depends on usage patterns. In reality I think that typically, HW heating costs are a small part of the energy consumption of a household that again I think what kind of system performance you want is more important.

Me, I generally prefer my stored HW. I like being able to have a backup for of heating the water. The important thing for stored HW of course is making sure that it will provide enough HW at the times you want it.

combi's are generally good for showers, as they use mains pressure HW, but bath filling tends to be slow. You can run 2 showers from one combi as long as it is big enough. A key factor though is how good is your mains supply, as it has to supply enough flow for the demands (ours probably wouldn't be much cop for example as the flow rate isn't that great, probably down to the dinky steel mains pipe that is probably half full of scale)

Then there are alternative systems such as mains fed unvented tanks like Megaflo.

Reading around to get more idea of the options and pros and cons is probably the way to go, and I think Agile's suggestions of paying someone to advise on the system is a good way to go if you aren't sure which way to jump. A new system is expensive and you don't want to get it wrong

 

[Agile]

This idea that a combi is unreliable and expensive to maintain is a total mith.

If you don't have a combi then you still need a heat producing boiler which still has most of what is in a combi to go wrong. PCB, pump, gas valve fan, flue flap etc. Then you have a cylinder to leak or split etc.

Modern boilers are very reliable indeed which is why the makers can give five years warrantee.

The heat loss of a cylinder is about 2-3 kWh per day costing about 15p of gas to make up. During the winter that heat loss contributes to heating the house anyway!

In return you get the ability to fill a bath in about four minutes.

But cylinders do need to be sized correctly and its always better to slightly over size them.

The rule of thumb I use is 50 li plus 50 li per person. So three people would deserve a 200 li cylinder.

A combi has its place! That's in a small flat where space is at a premium and only one or two people live there!

Tony

 

[Galoka]

A combi has its place! That's in a small flat where space is at a premium and only one or two people live there!

+1

 

[ivixor]

We have a seperate system with a pump for the HW. 2 young kids. Haven't had any problems, the water heats up again in 20 minutes if it ever gets cold, and you have torrents of hot water on tap. Also, it's been entirely reliable for 4 years, except for one valve motor needing replacing. The boiler is so simple there's not a lot to go wrong, so I expect it will be running for many years yet.

Oh and my mother has gone through two different combis during that time, both very troublesome, failing with all manner of inscrutable error codes.

 

[Agile]

And I could have repaired your mum's boilers!