Personally I would run the system as is for a year to see if it is adequate and if any other improvements in insulation etc could reduce the size of boiler required.
Many years ago a 160k BTU boiler would have been a commercial boiler and it was then cheaper to purchase 2 separate domestic boilers and run in parallel using non-return valves to prevent unwanted water flows.
That might still be the case, although you would then need 2 flues.
Yes, it's just dawned on me that 4000 litres might be closer - that would make a boiler replacement much more sensible. I need to wait for real usage data.
During the discussion I've moved to the same point of view - wait and see because the break-even is so heavily influenced by the actual oil consumption. Blindingly obvious with hindsight but it's been useful to have the discussion.
It would not be cheaper to install two boilers in parallel these days, even leaving out the maintenance and increased failure risk. Brings to mind the explanation for why Lindbergh chose a single-engined aircraft: with a twin there was twice the chance of engine failure and the remaining engine would not be capable of completing the task.
Wozzat in kW? 45 ish, thats rather big. How big is the house? We have a similar vintage and size Mistral oil boiler but it's heating more or less the volume of 2 three bed semis.
If it's like ours its a gert lump of cast iron that hold 12 gallons of water with a baffle plates up the central hollow hole in the top for the flue, hole in the bottom for the burner. They are supposed to have a clean out, jet, oil, filter and flexable oil hose(s) changed and electrodes adjusted every year. But they are so bog simple they generally "just work".
changing it
Probably not a lot. Every time ours has been serviced the flue gas temperature indicates an 80% effciency, that does tend to be not long after it's been fired up from cold though.
whether
I don't think you'll see a 25% improvement, that implies 65% or lower now. We used to get through 4,000 l/year but improving insulation, removing gale force draughts adding a 11 kW wood burner (7 kW to water) has knocked that back to 3000 ish. Bear in mind this is a large, high and exposed property.
You could ask the sellers how much oil they get through as a rough guide. That does make assumptions about life style, how hot/cold they have the place and how good the control system is. When we moved in here the heating thermostat was in one of the coldest rooms and didn't have a radiator in it!
I might borrow that. B-) It's easier to type than guesstimation.
Also to reinforce your decision, retro fitting a condensing boiler to existing rads is not likely to achieve the stated efficiency. To get even near the published figures, the flow/return temps have to be lower and so the heat output from the rads will fall. You will have to up the flow temp and sacrifice efficiency or fit new bigger rads and allow for that in your capital outlay.
When a rat died in our loft I investigated how to lift the large MDF boards that the previous owner had fitted, in order to be able to locate it. I undid all the screws securing on a board, as a trial. I chose a board at a corner so if there was any tongue and grooving, the board would slide out.
But the board wouldn't move. Not even slightly. There were no nail heads visible, so I can only assume that the stupid who had boarded the loft had glued the boards to the rafters as well as screwing them down :-(
Fortunately I found that the rat had considerately died just within arm's length under one of the boards that was open to the side near the eaves, so I was able to reach in with a plastic bag on my hand and remove the very smelly corpse.
It still took a few days for the lingering aroma to dissipate.
That price sounds a tad low to me. l was qouted over £5k by more than one source for a new 65k BTU oil boiler fully installed, not surprisingly l kept my old one.
Crittall windows are a disaster as far as energy loss goes. Secondary glaze them all, or contemplate replacement. DG on Crittalls won't solve it - not that I've ever seen that done, or are sure how it would be.
but blowing polystyrene beads or cellulose in isn't.
It's the absence of such ROI reasoning that allowed the billions of pounds to be frittered away on solar farms and wind turbines by the government fulfilling the manifesto promises made purely to win votes away from the Green Party here in the UK. I guess even the most basic "Back of a pack of ciggies" long term investment costs analysis were too much of an "Inconvenient Truth" to be raised as the entirely reasonable objection to implementing such projects beyond the level of small scale proof of concept.
If it was built since 1920s it will have a cavity as that was when it became requirement everywhere. Cavity walls have been used since 1870s in some areas. ie my house was built before 1900 and has a cavity.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.