MortarThePoint

I spoke to Wavin Technical yesterday and they said they don't get complaints about using Hep2O with compression fittings and it should be fine. They reiterated the preference of using a copper rather than brass olive and importance of using the insert. True knowledge comes from experience, of which I have very little. Can you share some of your experiences here? Have you had leaks with Hep2O and compression fittings in the past (grey pipe of white pipe?)? Have the leaks presented themselves straight away or worse after some time?

Yes it is, but I phone a few of the IDNOs and they didn't seem very good. Can you suggest one?

A warning to others not to make the mistake I did. I had a 3-phase connection to a building that was demolished to make way for the new build. I paid UKPN for a disconnection (£451) and am now looking to pay UKPN for a new connection (£2,441). If I had been wiser, I could have moved the connection for £1,345. I am going with a meter kiosk near the pole, so I could have just done that once saving £1,547, but even doing it twice to have the meter somewhere else after the build would have saved £202. At least I saved a meter standing charge which would have added up to about £600, but I guess I could have had the meter disconnected and saved that. £2,441 feels like a lot for a new overhead connection to a pole right next to a kiosk. It will take their engineer(s) about an hour I expect and it's probably less than £100 worth of cable and ducting needed.

BCO is strict about TMV requirement for baths and showers have them already. I'm wondering if I can set my cylinder temperature low enough to not need a TMV. That would make whole system run at the restricted temperature (45C?). I can't think of a reason we'd need warmer than that at any taps. A cooler tank is good for ASHP efficiency but not so good for hot water volume. That should be fine though. Tank would probably have to do some legionella magic periodically though so that may be tricky / make it impossible. I suppose the legionella cycle could be done using an immersion heater wired in parallel with a NO 2-port valve that closes whilst the water is too hot. There's a time delay issue there, but is anything like this ever done?

Cell balancing is a definite requirement as far as I am concerned and it's surprising/unforgivable if the Pylontech batteries don't feature it.

@Nickfromwales 🤯 pretty scary photos

(17*38.63 + 7*16.21) / 24 = 32.09 Assumes uniform use. Hard to adjust to the new prices. Economy7 is about what peak used to cost.

Simple calculation to work out the SCOP required for ASHP to be cheaper than oil: SCOP > (elec_cost_kWh) / (oil_cost_litre / (10.35 * oil_boiler_efficiency)) Where 10.35 is the kWh per litre of oil. A modern condensing oil boiler has an efficiency of 92%, so that becomes: SCOP > 9.5 * (elec_cost_kWh) / (oil_cost_litre) Today, for me that works out as: SCOP > 9.5 * (32.09p) / (54.43p) SCOP > 5.6 The 32.09p/kWh figure is a weighted average of peak=38.63 and Economy7=16.21. If I had battery storage (guess 95% efficiency) the elec_cost_kWh=16.21/95%=17.06. SCOP > 9.5 * (17.06p) / (54.43p) SCOP > 3.0 Remember, SCOP is the average across the season, so not the worst performance when -5C outside or the best performance when +15C outside.

Has anyone successfully claimed VAT on their energy storage battery or hear of it being done? Same goes for the inverter charger. Might wall mounted ones be more 'claimable'? I'd like a battery system and need to size it for expected ASHP demand, but probably something like 15 - 20kWh. That's 3 or 4 server rack batteries a charger and hybrid inverter (are they combined?) So probably looking at £6k+VAT. Would allow me to effectively use E7 electricity during the day when air temps are higher so COP better. I expect I would need to have an inverter capable of sustained 5kW to allow ASHP at full wack, lights and cooking. Options I'm considering: Fogstar 5.12kWh: https://www.fogstar.co.uk/collections/server-rack-batteries Fox ESS LV52: https://www.itstechnologies.shop/products/fox-ess-lv52-5-12kwh-48v-battery-module Pylon US5000: https://batteryfactory.co.uk/products/pylon-us5000-4-8kwh-li-ion-solar-battery-48v Premium Lithium system: https://premiumlithium.com/products/tripod Solis hybrid inverter: https://www.ginlong.com/global/inverter.html Useful resource: https://dcguy.co.uk/server-rack-battery

I thought I would share by deliberations on pipes for the feed and return to UFH manifolds. I have an 11.2kW ASHP and two main Manifolds meaning the peak power a manifold is around 5500W. Based on a dT=5K, that works out as a flow rate of around 5.5W/(5K*4.2kJ/K.kg) = 0.26kg/sec = 943kg/h = 0.94m3/h. My head calculations when considering a circulation pump were based on 28mm Hep2O. I was considering using 26mm multilayer pipe with compression fittings, but it turns out that would be much more resistive (~55% more) and the higher flow speeds would also be noisier. I expect a peak flow to a manifold of around the 946kg/h line of the table. For the multilayer pipe that works out as 4.27mbar/m or 154mbar=1.54m of head loss for a 36m run. Hep2O on the other hand the drop would be 0.276kPa/m=2.76mbar/m or 99mbar=1m of head loss for a 36m run. That's a 55% difference. If flowing 50% of the time, the difference in electricity use would work out as (24*365*50%) * ((0.26kg/3*9.81N/kg*0.55m) / 50%) = 12.3kWh/yr. Not much. I'd be more worried about being closer to the 1m/s advisory limit for flow rates based on noise. The multilayer pipe has the advantage of holding a shape when bent to it and more reliable fittings. It doesn't suit my situation though as I can't easily change to the larger 32x3.0 size that would be needed. 28mm Hep2O looks to be the better choice.

One aspect this neglects is all the bends in the UFH pipe. They aren't sharp bends, but with a bend radius of around 12.5x bore if a 90 bend or 6.3x bore if a 180 bend. Using this tool [1] I get pressure drops due to bends of these sizes of equivalent added length of 67mm and 96mm respectively. There is one such bend every ~3m so that's a pretty small addition of around 3%. [1] http://www.pressure-drop.com/Online-Calculator/

@JohnMo When you are running less than peak power, the flow temperature goes down, but does the flow rate go down too? I guess it can go down since the water dT between room and water is lower and so to get the same flow vs return temperature difference, the flow would need to slow down. I expect to be optimal, you want the dT of at the ASHP to be the same as the dT at the UFH manifold. That wouldn't be the case though since I think the ASHP circulation pumps will run at constant speed.

Both pumps would be around 50% efficient. The Ecocoirc-L running at 4m and 2.31m3/h would be 50W of shaft power which I guess is the same as electrical input. The Ecocirc-M at 3m and 2m3/h would be 33W of shaft power. If that is the electrical powers too, then using the Ecocirc-M would save 149kWh/yr = ~£50/yr. It's running closer to its curve limit. Not sure what that means in terms of lifetime.

I kin of expect my operating point to be at a head of 3m which is better suited to the Ecocirc M (3m constant pressure setting) than the Ecorcirc L (2m & 4m constant pressure settings]. However, 2m3/h would put it right near the maximum flow rate for the Ecocirc M at 3m head. Running the pressure 33% higher (at 4m rather than 3m) would put up the flow rate by 18% [1.33^(1/1.76)=1.18] and the hydraulic power by 57%, probably the electricity consumption too.

Here's a video of just attaching it to the stringer https://youtu.be/Pmyaw2TPUhk

Thanks How far does the first step of the upper flight overlap the half landing frame? I've designed it so that the riser is flush with the frame edge and it's only the nosing overlapping. That doesn't allow for any intermediate (internal structural) open stringers to notch on to the landing frame which would be nice for support. I hope that makes sense.

JAS Timber offer a service of cutting the mortice and tenon for you, but they are in Lancashire which is far from me in Cambridge. https://www.jastimber.co.uk/newel-mortice-stairs-1-tenon

Below is an example of the Newel / Stringer mortice and tenon. @dnb I see you've just installed a Stairbox kit with half landing. How do they do it? Is it a tenon on the stringer into the newel post? http://www.builderbill-diy-help.com/building-stairs.html

I know you can buy kits etc, but I've always wanted to make the stairs myself and I plan to do it in the way they typically do in the US. Make a rough stair and then clad with the trimmings. That said, I think it makes sense to use nice timber for the Stringer. I have created some CAD and the plan is to create a half landing frame, that the stringers attach to and the OSB half landing goes on to. Currently I have Newel posts just notched onto the half landing frame and the upper stair stringer, but I think I would like them to form uprights of the half landing frame by extending all the way to the ground. That may be too ambitious and increase my chances of making a hash of it. If I was to do it, the upper stair stringer would need to bolt onto the Newel, rather than notching onto the top of the half landing frame. Perhaps it would be better as a tenon into the Newel, but that would be an interesting tenon to cut and I don't have a morticing machine either. I think the Newel posts and the nosings are the only bits that are eluding me at the moment. Currently the stringer is 45mm x 220mm timber. Going is 220mm and Rising is 195mm. Newel height currently arbitrary.

The Lowara pumps actually have some additional goodies over the Grunfos: Constant pressure mode (modes 1, 2 3) as well as proportional-pressure (A, B, C) and constant speed modes like the Grunfos (I, II, III) Option to have a display and Bluetooth (adds about £30 ex VAT) Best-in-class energy efficiency (EEI ≤0.18) vs Grunfos EEI≤0.23 Both state Sound level ≤ 43 dB(A) Lowara are also about half the price of the Grunfos. So even if they don't last as long, they could be a better option.

The Grunfos UPS2 does pretty much what I want in terms of pressure / flow control (see below). When an UHF loop shuts off with an old style pump, it will maintain the same flow rate by upping the pressure which isn't what you want as it will increase the flow in the other loops. I want the differential pressure at the UFH manifolds to remain constant. If there was no head loss in the manifold feed/return lines, that would mean I wanted a pump that has a constant pressure output. However, since there is head loss in the manifold feed/return pipes, the pump needs to make a slight reduction in output pressure. I guess that is what UPS2's proportional-pressure control is intended to achieve, but I think it may be a little bit too sloped. In my example in the first post, there was 3.1m of head loss associated with the loop and its feed valves and 1m of head loss due to the manifold feed/return pipes at the furthest manifold. If half the loops shut off, manifold feed flow rate would half and the pressure drop in those pipes would go down to about 0.3m head loss. I have probably overestimated the 'loss at manifold' as it makes sense for that to be near zero for the longest loop and higher for shorter loops to try to balance. If it is zero, then I would need a proportional-pressure control curve which was linear from (0m3/h, 2.1m) to (2m3/h, 3.1m). PP1 looks to go from (0m3/h, 2.1m) to (2m3/h, 4m), so I guess that would increase the flow slightly in loops when valves shut off. It gets complicated by the different flows and lengths to different manifolds, but hopefully not too much. I have one manifold (3 ports connected) that is in the plant room, so has very short feed/return pipes. This feels better served by 22mm pipes and perhaps a manual orifice/valve. Even if the manifold differential pressure changes by 50%, an unrestricted loops flow would change by 26% [1.5^(1/1.76) = 1.26] so power delivery would rise by around that same figure, perhaps 30%. Orifice pressure vs flow relation is similar to pipe, so OK modelled by the 1.76 power. Of course, if I go the @JohnMo route of having no actuators, it will be balance and forget. Very tempting! I watched a good Heat Geek video about how shutting off a zone can mean that you up the heat demand in the still active zones (due to uninsulated internal walls), which ups the flow temperature, lowers the COP and actually costs more. Many variables, like house geometry, but it does make sense.

I'll use the pumps they have supplied for the ASHP side of the low loss header, but I need a pump for the UFH side of the low loss header.

It's all UFH. 12 loops upstairs and 13 downstairs.

Different floors, but I am hoping that doesn't matter