Wil

I bought myself one of the clarke gas/gasless jobs for christmas to try and re-learn what I knew when I was 16. Sadly, so far to call my welds birdshit would be a kindness. I've played with settings, but just can't get it right 😞

Thanks Dave, interesting on the 2P- 3P thing- this would increase the number of valves but I guess provide some level of resilience? and no let through as the valve changes position? So basically the GSHP does the heating direct, or if the TS is hot, it does the house and the GSHP switches off? I hadn't really considered that but might be a good shout. I'd have to be careful to size the TS correctly to get decent heat out. I suppose if it was a little smaller it could pass the heat from the fire on quicker. Would you put the oil into the TS or just run it direct like the GSHP? If the TS isn't fed by the GSHP or Oil, does it just become a heat source like them until it's temperature drops to a level where the TS or GSHP can do better? I have it in my head that simple relay control could do most of this but getting a simple and reliable control system may be more complex than I imagine!

Hi all, I’ve been living with the cold farmhouse over the winter since we moved in last year. We have an old oil burner which heats some rads in an open vented configuration. Also a small gravity fed DHW tank which appears to only heat from an immersion. It’s time to drag our house kicking and screaming into the present and prior to some extension works, I’d like to get the basics of the heating system in place. I’m lucky enough to have plenty of space in a plant room (old garage) next to the house and the time to start again. I’ve used Jeremy’s spreadsheet to come up with a 28kW heat loss for the house. I’ve done the obvious like stopping unused chimneys and filling the loft with 350mm insulation (50mm existing micafill, 300mm earth wool). But it’s still a leaky old place with 2ft thick solid stone walls. See attached diagram for my latest hare-brained scheme. Here’s where I need the collective smarts of those present to critique it and point out my glaring errors. I have access to a relatively cheap 22kW GSHP and can probably do a lot of the install work myself so considering that route. I’d keep the oil burner as a backup/ top up for a few seasons to ensure the HP and other systems were doing enough to keep us warm. I’m not going for the RHI as I know I can’t have a backup burner there. I plan to fit 3.68kW solar PV per phase onto my 3 phases to give an 11kWp solar system although almost all my load is on L3. L1 and 2 will almost always be surplus when the sun is shining (usually 50W each phase base load) which can dump into water/ heating/ PHEV/ future batteries. DHW is simple enough in that a new UVC with a large coil to take the output from the GSHP (or oil in super cold times). It would then have two backup/ dump immersion heaters to take solar output when available. There’s a passive coil through the TS to put a little heat into the water before it reaches the UVC. Heating is more complex and hence the interest in a Thermal Store to correlate some of my heat sources. As part of the extension works I have an opportunity to site a wood burner with back burner close to the plant room (while also useful in the house). 1. In times of high demand with only the GSHP/ Oil available (we’re not in and haven’t lit the fire or the sun hasn’t been shining and the TS isn’t hot) then the GSHP would bypass the TS and feed the rads and UFH direct. 2. As soon as there was heat from the fire or the TS was up to temp from excess solar, the GSHP would switch to a coil in the TS and the TS would feed the heating system (the 3P valves changeover on the TS/ GSHP loop). This would allow the GSHP to run against a buffer tank as well (although apparently it’s an inverter driven HP so should be able to just ramp down). Basically- what have I missed and why won’t this work? I could just drop the whole TS and wood burner idea and have the oil/ GSHP direct feed the rads and floors, but I think I’ll have excess solar in the shoulders and summer to be able to dump into the tank. Are the 3P valves a nightmare waiting to happen? What do I do about expansion vessels in this scenario? Thanks in advance for your help.

Just on the estate agents- How is that beneficial if they don't sell at asking? Obviously if you get more than asking, a fixed price helps, but on a percentage of sale, they take the pain of achieving any less than asking price along with you. On the OP, trust needs to be built up and it's hard choosing who you can build it with, but keep communicating as that's where it always starts to go wrong.

From the Salus website: first bullet point would appear to be a problem for you. A WORLD FIRST IN UNDERFLOOR HEATING TEMPERATURE CIRCUIT BALANCING & ENERGY SAVING Each Actuator has two temperature sensors which are clipped onto the flow & return pipes (one on each) of the circuit to be controlled. The Auto Balancing Actuator will measure the temperature sensors and adjust the valve position to maintain a constant 7°C temperature differential between the emitter flow and return pipes. Not compatible with Heatmiser thermostats Very Low Power, less than 0.5W Fast actuator opening and closing times typically 30 seconds....

And how long for on average? a 1500W computer UPS should hold 320W for half an hour or so? Is the sewage treatment the only critical item you'd like to keep on? If you went down the critical route you could split some other supplies like fridge/freezer or possibly just put a 5*kVA genset in to cover all house loads (obviously it would need to be sized for actual load). I think most people find it's rarely worth it for the genset, but depends on how often you have the issue.

Given the size of the property, what's the size of the heat pump? a 20kW heat pump will be using 5kW of electricity on full steam and if you run it with all the doors open (as per pics), it could easily be doing that. A HP is more efficient than chucking direct electric at the problem, but not if just left on. I'm tracking my consumption and our 5 bed farmhouse is currently averaging around 30kWh a day without any heating on! But we do charge an electric vehicle most nights which accounts for a decent chunk of that. Immersion for water and electric cooking account for most of the rest. The instantaneous and daily readings (particularly when it peaks and troughs) would be really helpful to understand where you're using the energy. Edit- sorry I meant to ask- does the business/ retreat form a separate meter from the house or is it all one property?

Yes, my apologies, got carried away when I saw the price and total thread hijack. Thanks for the answer though, I'll have to look into whether there's some sort of controller that could bring these in and out depending on demand.

Is there any reason for me not to buy two of these instead of a 22kW GSHP and run them in parallel in a high heat requirement situation?

Thanks PeterStarck, I think I read your postings on it. Yours was newbuild and designed with Icynene in mind though right? I'm concerned about the application to an old existing building. It certainly sounds like a great option, even if only used as posh cold roof insulation to ensure all the air leakage is stopped there. So many different things to think about, but for now, it's going and getting the keys tomorrow that'll keep me up tonight..

Thanks Peter, I have 3phase available, so not limited to single except on the complications of using solar to offset it. Will probably end up with 3 single phase solar arrays though so again can offset daytime heat pump use to a degree. 14kW doesn't sound like it'd cover my peak losses though? I was looking GSHP over ASHP only due to capacity/ efficiency for the size I'd need. I do have a friendly MCS certified installer and digging holes to put pipe in shouldn't be too much of an issue. HP = Heat Pump Cylinder right? Where does this differ from a UVC cylinder? (will google shortly). Out of interest, why 400lt? Is that to give cover for the recovery time using a ASHP? There's a large airing cupboard in the bathroom so a DHW tank in the middle of the house isn't an issue. Appreciate this is a heating conversation but is Icynene a reasonable idea for insulating and sealing up a leaky old building? Looking for breathable and minimum impact on depth, but afraid of a sticky mess requiring a new roof!

thanks Miek, I have calls in with Kensa and ThermalEarth to discuss GSHP options, so will see what they have to say. I did wonder if my lack of air tightness would preclude a ASHP option, or I may need two in series. Good point on the replenishment of the water needed. There is a pond at the property too but I'm not sure it's big enough and I haven't seen what it looks like in summer to see if there's any water in it all year round. I suppose there's no reason to completely scrap the oil burner and this could be used as 'top up' on any lower temp heat sources. But it can't have long left in it being at least 15 years old.

Ain't that the truth 😑ton of energy indeed, hence the desire to combine sources. Yes, you're right in trying to get the ceiling airtight. The cold roof is indeed cold and when I stuck my head up there in February, the howling gale almost took it off. It does have impermeable felt under the roof tiles, but appears to have some fairly major daylight gaps which may need dealing with swiftly. Particularly as I'd like to put the heating manifolds up there and any other plant in place of the large pair of cold water/ expansion tanks currently occupying it. The worst offenders are likely the light fittings and pipe penetrations between the 'warm' house and cold loft. Peter- Slaving the UVC off a thermal store sounds interesting- effectively the ASHP feeds both and when the UVC is satisfied it runs into the TS? In the summer, just run the ASHP into the cooling manifold for the fan convectors? As mentioned I'd have plenty of room to divert solar into immersion heaters for either TS or UVC. Possibly some solar HW to pre-heat the TS or do the UVC in summer? Or is that just overcomplicating things? It feels like Solar HW would always have somewhere to put the heat! One other point- the current owner mentioned an abandoned well outside the backdoor which her late husband had been considering for some sort of water-water heat pump, but had never gotten around to. Is this so niche it's unlikely to be an option? Thanks

Internal features are coving details and multiple wall angles/ returns that would mean internal studwork frames being very complicated and eating a lot of the space. Also means every skirting board, picture rail and socket/ switch need redone. Given it's a farmhouse- in the summer it's likely to live with the back door open most of the time, so mainly winter heat losses to deal with.

Thanks all for the replies so far. I have a reasonable line in CAPEX available for the right solution (this one is going to be a forever home- no really- that's not what I said about the current house, but this one is). So realistically OPEX more of a consideration within reason. GSHPs look good for the RHI to cover install costs. We will have our existing place available til it sells, but realistically will be moving over fairly soon, so piecemeal improvements rather than a complete refurb. The rooms I'd consider UFH are currently unheated and have much lower floors for some reason already, so there's easily 100-150mm of space for insulation and UFH by just going directly onto the existing floor coverings. You're right about the heat loss being high though. I'd certainly look to deal with some of the leakage via chimneys where we're not using them for woodburners. no issue with blocking them up as needed, but it feels unlikely the whole place will reach decent air tightness without major work. DHW through a UVC is a good call (except I'll need a person with quals to install it) I wonder if a thermal store for collecting various heating systems and a separate UVC for DHW is overkill? I could go down the pellet boiler route, but for the horror stories around blocked augers etc. I'd rather go a gasification boiler with some of the wood we have available on site? Then again, I'd prefer to use some sort of heat pump covered by PV/ economy tariffs to have a system that didn't need feeding and meets the WAF. Could I 'stack' ASHPs or have an upstairs/ downstairs arrangement?