@old_scientist and @allyfish , thank you both for this. We currently have a 23yr old Oil boiler, installed in a then new-build. I have no doubt that some of the sludge festering in the pipe and emitter system is of the same vintage.

I am fairly confident we have 22mm F&R from the boiler going up and around the first floor, with 10mm u-bore teeing off to all the rads on both floors. the ratio of 10mm to 22mm copper is unknown and will only be bottomed-out by inspection with a Mk I Eyeball, viz. by lifting the first-floor boards; which no doubt are chipboard, just for added interest to the task.

We are moving into retirement mode, hence will be spending more daytime at home; and given the Oil boiler has passed its prime it will likely need a "tech refresh" in the nearer future too. This why we are considering ASHP for our energy needs; likely looking at PV solar/battery too. Insulation is 'ok', building heat loss is 9.6kW. Windows were replaced 2017 and the loft will be treated to another 150mm duvet.

One plumbing option is to re-pipe the first-floor copper with fit-for-purpose sizes and spec-up rads for a high-flow, lower-temp air-source system. The intent is to route into the ground floor concrete to lay pipe throughout for UFH. Admittedly it'll be a huge disruption, albeit only a few weeks; but we are fortunate to have a contingency for temporary accommodation, namely a caravan.

Mad ? ... borderline ... but more a case of investing in our future energy needs, with lower running costs while delivering increased comfort as our needs change over time. We're not really looking for ROI, per se, although it won't be long into the future where oil-fired heating will reduce a property's marketability and sale price: just my pov.

Posted by: @colinc

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Mad ? ... borderline ... but more a case of investing in our future energy needs, with lower running costs while delivering increased comfort as our needs change over time.

I had similar thoughts with my heat pump and, to a lesser extent EV (I have had solar panels from 2011).

Having made the leap I have absolutely no regrets with either.  Both are a far superior experience with lower running costs and a reduced dependence on foreign despots.  Of course they complement the solar as well so Im now pretty well insulated from energy price fluctuations.  My original motivation was largely environmental but actually there are very immediate personal benefits.   

I don't have batteries yet, because I cant quite make the business case work and I cant see a robust environmental case.  There will come a time when it will, I'm sure, at which point I will do that also.

@jamespa Likewise in many respects; we don’t have an EV or even a push along scooter (poor sight, keep death off the roads!), however, we do have a battery. ‘Twas expensive and thought of slightly as a luxury; with continuously rising energy prices and the availability of TOU tariffs, that luxury is now more of a bonus!

We have solar panels and we have very good insulation; all these investments provide a warm feeling too. We have a heat pump and are all-electric and thus don’t have a gas meter or pay more than the one standing charge. We reclaimed our investment from the bank as we had paid on a credit card for a Wind Turbine project that went down the pan and we are still awaiting our first payments (possibly next summer) on our solar farm project investment. Regards, Toodles,

@jamespa

Well, you must have been an "early adopter" for solar panels; what I describe as "bleeding edge" as opposed to the 'leading edge", and will have gained considerable experience over that time as this industry has developed.

I would agree there are many positive aspects for the environment for solar panels, athough my buy-in is somewhat limited to the way that lobbyists (corporate, environment & academia), MSM, and political factions 'across the house' are 'weaponising' the whole environmental debate to suit their own agenda and objectives. Basically, the 'room' needs some adults present who are not hell-bent on pursuing their confirmation-bias; sadly a human trait that bears no fruit.

Regarding batteries and the environment I take your point, and have seen first-hand the way rare-earth extraction continues to  blot and poison the landscape in The Congo and DRC: the West is as much a culprit and catalyst as China. Maybe the development of exploiting sodium, perhaps replacing lithium, might change this; albeit it's a different 'beast' in terms of its capability profile currently.

In my experience a Business Case can be skewed to suit the aim; one only has to look at HMG's decades of fairly regular incompetence since WWII for examples.

I doubt much will change on my watch, so meantine I will be investing in PV & Battery as the "better evil"; and as you suggest, achieving a small level of energy independence.

@toodles

The practicalities of investing in Wind and Solar is something I no little about; and although it does sound interesting, rightly or wrongly I am not very motivated that way. There seems to be multi-billion £/$ investment pouring into large scale battery storage currently, which is really the only way to make sense of the billions already invested in wind and solar energy. It's a shame that tidal and wave energy has not gained much traction in R&D investment.

The cynic in me suggests that because it's fairly low-tech there's not enough of a "big bucks" incentive for corporate entities to exploit. That said, at their source: sun, wind, and sea energy capture are all fairly basic technically. The operating environment and the energy storage is more of a challenge.

However, we seem to have the gumption to put wind turbines and solar panels in almost any environment, so why not corall the tides and waves on an industrial scale too ?

Last time I looked at a map we are pretty much surrounded by water; depending of course on one's view of nation boundaries, but I live in hope.

Posted by: @colinc

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@toodles

The practicalities of investing in Wind and Solar is something I no little about; and although it does sound interesting, rightly or wrongly I am not very motivated that way. There seems to be multi-billion £/$ investment pouring into large scale battery storage currently, which is really the only way to make sense of the billions already invested in wind and solar energy. It's a shame that tidal and wave energy has not gained much traction in R&D investment.

The cynic in me suggests that because it's fairly low-tech there's not enough of a "big bucks" incentive for corporate entities to exploit. That said, at their source: sun, wind, and sea energy capture are all fairly basic technically. The operating environment and the energy storage is more of a challenge.

However, we seem to have the gumption to put wind turbines and solar panels in almost any environment, so why not corall the tides and waves on an industrial scale too ?

Last time I looked at a map we are pretty much surrounded by water; depending of course on one's view of nation boundaries, but I live in hope.

and we have some of the strongest tidal flows anywhere on the globe.

@jamespa most I've ever seen is 5 and often 4, surely any more than two and you need to ask 'why?'

Posted by: @dgclimatecontrol

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@jamespa most I've ever seen is 5 and often 4, surely any more than two and you need to ask 'why?'

I assume you are referring to this post https://renewableheatinghub.co.uk/forums/postid/50045/ and yes indeed you do have to ask why!

@jamespa Yes that post.

@colinc good luck with your project!
UFH is the absolute best from both comfort and ASHP efficiency. We have it in the extension and wish we had elsewhere in the house. But we chickened out on initial house refurb since we have solid concrete floors and they would have all had to come up for the 6inch of polystyrene insulation to go in. The mess would have been horrible and even though we were still in rented we didn’t even get quotes for it. 
Sadly our surveyor said, ‘you don’t need to dig the floor up all UFH systems add insulation’ (2mm of it!). A quick calculation by us stopped that approach, using electrical ufh to heat the rest of the street via the garden, no thanks. That was 15years ago but the surveyor world hasn’t moved on much, just before the energy crisis a neighbour doing a refit had electric ufh fitted in his lounge in his solid floor house and found  it never even got the room tepid whilst nearly bankrupting him.

You are doing the right thing by planning for a water based system. You get the benefit of the COP on electricity usage.