Thouhgts on a new boiler - Combi?

ahar_2

So, we have an old, inefficient heating system that is costing lots and lots of money. We're looking at overhauling it (new boiler, radiators etc) and I'd be grateful for any thoughts people had.

Currently have an open vented system with the standard hot water tank in airing cupboard, cold water tank and header tank for heating system in the loft. The house is a 4 bed converted bungalo with one bathroom (with 13 rads), though we'll be putting in an ensuite in a few years time.

The boiler works okay, but some valves need replacing, the hot water cylinder is old and not very well insulated and the pump for the central heating is starting to break. The cold water tank in the loft is badly insulated as are the pipes, so that all needs sorting. Some rads are too small for the room, and others are really old and inefficient.

My thought was to go with a combi with attached storage, something like the Vaillent 937 - that way I could avoid sorting the tanks in the loft and the hot water cylinder, and the combi with attached storage would be able to run both showers fine for a short period in case they are both in use at once (the Vaillent quotes 20 l/min hot water for 10 mins, until the storage tanks run our, after which it's 15 l/min). Our current shower (helped by a small pump) uses 10 l/min (measured using a big bucket, stopwatch and simple maths), and I'm perfectly happy with it's performance so two of them for 10 mins will be fine.

However, I measured the water throughput from the mains, and it may be my cunning plan is not going to work. Ensuring the stopcock is fully open, I tested from the kitchen tap, the outside tap and the downstairs toilet tap (that's where the mains enters the house) at 2 different times of day, again using a large bucket, stopwatch and simple formula to calculate the volume of water in the bucket.

Earlier in the day I measured 17 l/min, but later on it was down to 14 l/min at best (and 11 l/min at worst). That feels far too low to use a combi boiler.

If I don't go for a combi, then I'm back to replacing the boiler and hot water cylinder, and sorting the pipe work and tank in the loft. I could go for a closed heating system which means I can dispense with the header tank in the loft I suppose.

Anyone install a combi with storage in a house with that kind of flow of incoming water? Other options I'm missing?

MillicentBystander

At the risk of sounding like a broken record, replacing an old, working, safe but inefficient boiler is rarely money saving. Plus the new fangled, sophisticated boilers they sell nowadays are in no way going to last as long as the one you currently have.

ahar_2

Replacing it will save money. I didn't say I wanted the entire investment to pay back based on the savings made.

I did mention there is investment required anyway to ensure the system remains working:

"some valves need replacing"
"the pump for the central heating is starting to break"
"The cold water tank in the loft is badly insulated as are the pipes, so that all needs sorting."
" Some rads are too small for the room"

victor2

ahar wrote: »

Replacing it will save money.

That is very doubtful as long as it is working.
It may reduce your ongoing running costs but will require a major investment up front, which will not pay back, in the short term or long term.
However, if you have the resources now to make that investment, which will be significantly more than the required maintenance to the existing system, then at least your future costs may be reduced. With the spiralling energy costs, that is an option I would seriously consider.
Similar to you, I could replace my ageing but perfectly reliable boiler with separate hot water tank and header tank in the loft for a combi boiler and sealed heating system. We have an electric shower and rarely use the bath, so a combi would be suitable. Just to change our non-condensing boiler to a condensing one will be expensive though. The current boiler is in an internal utility room with no outside wall and the flue goes up through a gap in the upstairs walls to the roof.
Just looking into the ways to sort that out put me off enough to say I'll keep running the existing boiler until it dies!

MillicentBystander

ahar wrote: »

Replacing it will save money. I didn't say I wanted the entire investment to pay back based on the savings made.

I did mention there is investment required anyway to ensure the system remains working:

"some valves need replacing"
"the pump for the central heating is starting to break"
"The cold water tank in the loft is badly insulated as are the pipes, so that all needs sorting."
" Some rads are too small for the room"

Chances are it won't. People tend to forget the not inconsiderable expense of the new boiler, it's not like you can honestly and accurately state the new boiler will be saving you money from day one. It won't, you may be using less gas but to do that you have had to fork out maybe £2,000! A saving of £100 a year on your gas, for instance, would mean the boiler has paid for itself in 20 years. And I would be really surprised if a combi survives that long (certainly without the need for expensive repairs).

PS The stuff that needs doing can be done without actually replacing the boiler now until it either dies or becomes unsafe, surely?

ahar_2

victor2 wrote: »

That is very doubtful as long as it is working.

Except it isn't working properly as I mentioned in my first post. It at least needs a power flush (around £400-500) as it's full of sludge. Also, some valves are broken (water flowing round the system when it shouldn't, rads not heating up properly etc), and the pump will need replacing in the next few months as it keeps stopping working.

It will save money each month, as the boiler and rads will be more efficient, and the hot water cylinder will not lose as much heat. Either less gas for same heat, or more heat for same volume of gas

Will the monthly savings pay back the investment? Unknown, as it requires some fixing now anyway and who knows how long the boiler will keep going. However, I didn't ask whether it will pay back the investment.

MillicentBystander

But this is primarily a money saving site where people try and give money saving advice and this we have given. Completely up to you whether you take it or not, of course. If you've convinced yourself that you are getting a new boiler no matter what there are more technical people than me on these forums who hopefully will pop on here and give boiler advice.

ahar_2

I know some work needs to be done, and we want to redecorate the room the boiler is in at the moment. I didn't mention this before as I didn't think it was relevant, but we want to redecorate the room the boiler is in currently, and due to recent safety standards there will need to be quite a bit of recofiguration when the boiler dies (for example, adding a pipe to take away the condensate) so we may as well group the work together rather than having to redecorate again.

ahar_2

Forgot to mention in my previous post, the other thing I didn't mention as it wasn't relevant to my question was how I'm going to pay for the upgrade. It's a long and boring art of circumstances , but there is a big benefit to me spending the money now to replace the boiler than in an unpredictable time in the next couple of years if the boiler fails and needs replacing.

Wywth

ahar wrote: »

So, we have an old, inefficient heating system that is costing lots and lots of money. We're looking at overhauling it (new boiler, radiators etc) and I'd be grateful for any thoughts people had.

Currently have an open vented system with the standard hot water tank in airing cupboard, cold water tank and header tank for heating system in the loft. The house is a 4 bed converted bungalo with one bathroom (with 13 rads), though we'll be putting in an ensuite in a few years time.

The boiler works okay, but some valves need replacing, the hot water cylinder is old and not very well insulated and the pump for the central heating is starting to break. The cold water tank in the loft is badly insulated as are the pipes, so that all needs sorting. Some rads are too small for the room, and others are really old and inefficient.

My thought was to go with a combi with attached storage, something like the Vaillent 937 - that way I could avoid sorting the tanks in the loft and the hot water cylinder, and the combi with attached storage would be able to run both showers fine for a short period in case they are both in use at once (the Vaillent quotes 20 l/min hot water for 10 mins, until the storage tanks run our, after which it's 15 l/min). Our current shower (helped by a small pump) uses 10 l/min (measured using a big bucket, stopwatch and simple maths), and I'm perfectly happy with it's performance so two of them for 10 mins will be fine.

However, I measured the water throughput from the mains, and it may be my cunning plan is not going to work. Ensuring the stopcock is fully open, I tested from the kitchen tap, the outside tap and the downstairs toilet tap (that's where the mains enters the house) at 2 different times of day, again using a large bucket, stopwatch and simple formula to calculate the volume of water in the bucket.

Earlier in the day I measured 17 l/min, but later on it was down to 14 l/min at best (and 11 l/min at worst). That feels far too low to use a combi boiler.

If I don't go for a combi, then I'm back to replacing the boiler and hot water cylinder, and sorting the pipe work and tank in the loft. I could go for a closed heating system which means I can dispense with the header tank in the loft I suppose.

Anyone install a combi with storage in a house with that kind of flow of incoming water? Other options I'm missing?

My thoughts are that you are probably on the wrong site if you are considering spending your hard earned cash replacing a working boiler

Get some new valves and a jacket for your hot water tank instead!

ahar_2

Wywth wrote: »

My thoughts are that you are probably on the wrong site if you are considering spending your hard earned cash replacing an old working boiler

Yes, it would seem so. Can everyone just pretend my boiler is broken and can't be fixed when replying?