Change my old CH boiler for a new one?

ming60

Thanks everyone, for your replies, and much valued information. I think I will first of all sort my loft out, and will probably have to rearrange it, as I have stuff stored up there over some of the insulation. I've also got 25% of the loft area boarded, so the insulation under that isn't efficient enough. The rest of the insulation is only 150mm thick, and just between the floor rafters, so that will need doubling up. Thanks to 'Hengus' for prompting me on this.
I will hold off sorting out the boiler for now. I'll see if by improving the loft insulation, it will bring down the amount of kWhs used.

ming60

[FONT=Verdana, sans-serif]Just an extra, in reply to Marmaduke123. I can't program the HW separately to the CH. The programmer, a Danfoss 103, doesn't allow it. From how I understand it, my gravity feed system is fully pumped. Does this make a difference? Sorry, but I'm not that clued up on these CH systems - Does it show!?
[/FONT]

FreeBear

misterbarlow wrote: »

When we moved in here 12yrs ago there was a baxi bermuda back boiler that looked from the 70 or 80s..
It was all working ok though and we were skint from the move etc, so I just re-lagged the tank and bought a better controller with digital timer, and kept it going..

Early last year we came into some PPI so decided now was the time while we had the cash to get rid, and had a new Worcester combi fitted..

I was expecting a nice refund and was only £18 in credit at end of year!!
We are not really saving anything at all.. maybe £1-2pm!!

I also have a vintage Baxi Burmuda. Also a low gas user, so any savings would be minimal. Had to replace the timer earlier in the year as it died of old age. Replacing the ancient radiators with modern ones seems to have made a noticeable improvement in keeping the place warm. Plugging all the draughts as I redecorate/renovate is certainly a major improvement.

Have thought about a new combi, but getting hot water in either the bathroom or kitchen means running a tap for ages. If the boiler is close to the bathroom, the kitchen tap is going to have to run for an age before getting hot water. Locating the boiler closer to the kitchen, then the bathroom would suffer the same problem. Either way, the combi would have heated up a pipe full of water that would go to waste after the taps are turned off. So no saving to be had there.

Fitting a modern condensing boiler (either a system or a combi) would save perhaps 15% on gas usage. If I'm lucky, that would be ~£70 a year. A replacement boiler would probably require new radiators to be fitted - This, I'm already doing. By the time I've replaced them all, it will have cost somewhere in the region of £400 including TRV valves and new pipework. Doubt it will save much on heating costs, but modern radiators are more efficient and look so much better.

As the OP is of pensionable age, it would be worth looking to see if the energy supplier will fit a new one under the government’s Energy Company Obligation (ECO) scheme. Contact a the big six suppliers, and you may well find one that will offer a grant even if you are not one of their customers. That said, it looks like funding ended in November although there is a possibility that new funding will be made available (hopefully) before April 2019.

https://www.ofgem.gov.uk/environmental-programmes/eco/support-improving-your-home

One more thing to add - A combi boiler is not going to make much difference in how fast the radiators heat up (maybe 10-15 minutes). There is a fixed amount of water in the system that has to be heated first. A new CH system may reduce this slightly, and a new boiler may heat the water a bit faster, but there will always be a delay.

System

macman wrote: »

Your existing system does not 'take heat away from the radiators' when you draw off hot water. They are two completely separate circuits: your hot water is stored in the hot water tank.
With a combi, you will have hot water on demand, but while you are producing hot water, no heat will be sent to the CH circuit.
I think you are confusing a combi with a condensing boiler. All new domestic installs are condensing, whether combi or conventional.
I agree with the comments that suggest that the existing system may be heavily sludged and could benefit from a powerflush (which you'll need to do anyway prior to a new install).
Either type of boiler gives instant, or near instant, heat to the rads. But only a combi gives hot water on demand.

If the system has been set up as HW priority, then whenever the cylinder class for re-heating then the boiler flow from the rads will be diverted to the cylinder coil. This is usually known as a 'Y' plan configuration. In an 'S' plan configuration, both the heating and HW zone valves can be open at the same time. I agree that heat will not be taken out of the cylinder. The OP appears to have HW priority. The 'trick' here is to do the bulk of the cylinder re-heating before you want CH.

macman

If you cannot control the CH and DHW independently, then invest about £80 in a modern dual channel digital programmer. Much cheaper than a new boiler...

ming60

Thanks again for all the helpful guidance and tips.

FreeBear... thanks for the info. I will look into that aspect of the government's ECO scheme. Yes, any saving on expenditure would be useful for us!

Macman.... thanks for the tip about the programmer. I'll check this out with my boiler servicing guys.

C_Mababejive

The glow worm hideaway is a fabulous boiler and they tend to last.

Id say if you want to spend money,consider uprating your insulation.

Another possibility might be to convert existing system to fully pumped depending on type of cylinder and fit a 7 day twin channel programmer.

merchcon55

macman wrote: »

If you cannot control the CH and DHW independently, then invest about £80 in a modern dual channel digital programmer. Much cheaper than a new boiler...

Siemens RWB29 si

You can get one for £39 off a well known auction site.


I have a glow worm hideaway - loads of different things you can programme - works very well.


There are other models - but make sure it is DUAL CHANNEL (separate control for Hot Water and for Central Heating)

System

merchcon55 wrote: »

Siemens RWB29 si

You can get one for £39 off a well known auction site.


I have a glow worm hideaway - loads of different things you can programme - works very well.


There are other models - but make sure it is DUAL CHANNEL (separate control for Hot Water and for Central Heating)

This is all good advice but programmers/timers need something to control; ie, for example, zone valves. The reason why the OP is using so much gas is because of the age of family members, and the characteristics of his home. The only thing that will use considerably less gas for a given heat output is a modern boiler BUT the savings accrued are unlikely to cover the investment cost of a new boiler.

Mister_G

Hengus wrote: »

This is all good advice but programmers/timers need something to control; ie, for example, zone valves. The reason why the OP is using so much gas is because of the age of family members, and the characteristics of his home. The only thing that will use considerably less gas for a given heat output is a modern boiler BUT the savings accrued are unlikely to cover the investment cost of a new boiler.

I note that the OP has replaced a 2/3 way valve. Looks like that may be to switch between heating HW and CH or both, so perhaps a dual channel controller is all that's needed?