Now it is fixed how can i make it more efficient ?

[andyinscotland]

My boiler is now fixed and working, thanks Oilman.

but it is an old inefficient model, band d or below i would guess.

it has a conventional flue ( cast iron ) that goes up into the chimney in the kitchen. i believe it replaced an old aga type thing about 14 years ago.

i have about 50 cm of this cast iron flue visible from the top of the boiler untill it goes into the chimney.

this flue becomes very hot when the boiler is in operation and these hot gasses are happily going up it to be wasted out the chimney.

is there any way i can recover some of this wasted heat?

after all the new condensing boilers do just that!

perhaps a water jacket round the visible part of the flue with the central heating return going through it before going back into the boiler?

or even coiling the cold feed round it before it goes into the heatbank to be heated for the hot water supply?

any thoughts or suggestions?

Thanks

Andy

 

[oilman]

Unfortunately you have a boiler which has a terrible design, and if the baffles get stuck, that's it for cleaning. If you break them, there's no replacement available.

Don't mess around with diy heat recovery on these things, you may give yourself a corrosion problem. Condensing is a poor approach to fuel saving compared with modulated operation. If you are not in the house all day, fit a timer to control the whole boiler, not just the heating. This makes it no different to the method used for a HW tank system, when you heat the water roughly when you want it. If you are home and using it, press the boost button. This will give you dramatic savings.

I'm sorry to say, but the best approach for efficiency is to buy a new boiler, and have everything ready for a changeover, then replace it when it breaks. Are you in a rural area?

About the only thing you can do is to clad the thing in rockwool to reduce the heat losses.

 

[tryitandsee]

Interesting thoughts.

To some extent the flue pipe is acting like a radiator and giving you some heat return to the kitchen. Also the waste hot flue gases are keeping your chimney dry and warm, helping heat the structure.

Where do you stop! I always think about the amount of energy needed to heat domestic hot water, then only to pull the plug from the bath and let it go down the drain. It's still reasonably hot and would be so simple to have a heat store that could transfer that residual heat into the incoming mains, prior to it being heated again.

I even think the same could be achieved with water pipes being coiled/buried in a compost heap, with all the garden waste keeping it going. It would probably look like a indirect hot water cylinder, but filled with compost, lid on the top, with a grate at the bottom letting out composted soil.

I guess that until energy costs get so ridiculously expensive, we will keep on being the same, wasteful.

 

[andyinscotland]

Yes im in a rural area. the gas supply stops about 5 miles away.
and i am about 40 miles from Glasgow.

Unfortunatly the house is occupied 24/7 (elderly mother and wife at home)
so turning the heating off during the day is not an option

i have been giving serious consideration to replacing the boiler, but as you know oil boilers are not cheap. especially the bigger ones like the worcester bosch 25/32 or the grant vortex 36.
i estimate it would cost between £3000 and £3500 to replace the boulter with either of these.
and that is outside what i can afford at the moment as i have just moved up here and it has cost a lot more than i had budgeted for.

perhaps next year when ( hopefully ) the prices have come down a little on the band a boilers and i have had a chance to save up some cash i can get it replaced, but i am stuck with it untill then.

thats why i am looking for a way to make it run a little more efficiently for the next year or so

 

[oilman]

Is the house big enough for a HW cylinder?

 

[andyinscotland]

Is the house big enough for a HW cylinder?

yes its big enough.

it did at one time have one i believe. there is an old galvanised water tank in the loft with some old iron pipework running to it.
all disconnected now but evidence of a different heating / water system at one time.

the loft access is very restricted at the moment though.

someone has in the past replaced the landing ceiling, and as a result there is only a 10" x 12" opening into the loft space.

But i guess i could make it bigger to get a new cold tank up there if i had to.

 

[andyinscotland]

Interesting thoughts.

To some extent the flue pipe is acting like a radiator and giving you some heat return to the kitchen. Also the waste hot flue gases are keeping your chimney dry and warm, helping heat the structure.

Where do you stop! I always think about the amount of energy needed to heat domestic hot water, then only to pull the plug from the bath and let it go down the drain. It's still reasonably hot and would be so simple to have a heat store that could transfer that residual heat into the incoming mains, prior to it being heated again.

I even think the same could be achieved with water pipes being coiled/buried in a compost heap, with all the garden waste keeping it going. It would probably look like a indirect hot water cylinder, but filled with compost, lid on the top, with a grate at the bottom letting out composted soil.

I guess that until energy costs get so ridiculously expensive, we will keep on being the same, wasteful.

now a heat pump combined with a big compost heap has some interesting possibilities. provided of course it diddnt freeze the composting bacteria

 

[oilman]

The economical route is to fit a new tank in the loft, a vented HW cylinder and a conventional boiler so you get rid of the combi function. You will have lower pressure at the hot taps, but you will have smaller and cheaper problems in future.

 

[andyinscotland]

The economical route is to fit a new tank in the loft, a vented HW cylinder and a conventional boiler so you get rid of the combi function. You will have lower pressure at the hot taps, but you will have smaller and cheaper problems in future.

i have thought about doing that.

i even considered adding a cylinder to the central heating circuit on this boiler just to get some hot water before it was fixed.

but the house has a bit of a weird layout and 2 bathrooms.

one upstairs and one downstairs ( granny flat) and both are at the other end of the house from the kitchen, ( boiler site) but one above the other.

i have traced some of the feed pipes to both the bathrooms, they are under the froorboards upstairs. 22 or 3/4" (it varies) to the upstairs bathroom then down to the one below.

so getting water pressure everywhare might be interesting

and just to add to the fun the other plumbing, for example the waste pipes are a combination of cast iron and lead pipes.

mating 40mm plastic to 2.5" lead was fun

 

[oilman]

As the HW demand for a kitchen is low(ish) put the cylinder at the bathroom end of the house, and put a small unvented (15l) electrically heated, in the kitchen.

 

[andyinscotland]

As the HW demand for a kitchen is low(ish) put the cylinder at the bathroom end of the house, and put a small unvented (15l) electrically heated, in the kitchen.

thats an idea,
but what about the boiler site? it is currently in the kitchen
the other end of the house from the bathroom,
so the feeds to the indirect coils in the tank would have to run across the house to it?
or use an immersion on it ?

or site the tank anywhare and add a flow switch and pump on the outlet pipe from the tank to get a bit of pressure in the hot water ?

would have to be carefull not to collapse the tank though.

ow my head hurts

 

[oilman]

Put a vented tank in the bathroom end, with its header tank, then replace the boiler next year with one nearer the bathrooms. Leave the HW as is for now, or use an immersion heater to run the tank. until you shift the boiler. You could also tap off the heating circuit near the bathroom to feed the tank until you change completely. Not ideal, but it does provide a fix.

 

[andyinscotland]

Put a vented tank in the bathroom end, with its header tank, then replace the boiler next year with one nearer the bathrooms. Leave the HW as is for now, or use an immersion heater to run the tank. until you shift the boiler. You could also tap off the heating circuit near the bathroom to feed the tank until you change completely. Not ideal, but it does provide a fix.

not a bad idea m8.

if the hot water side of this old combi goes again i might do that.

fingers crossed it lasts till next year and i can sort it out when i have a little more spare cash