MortarThePoint

ASHP kit has come with two LOWARA 25-8/130 pumps and the supplier's schematic shows these on the flow and return pipes to the actual ASHP itself (from the low loss header). The schematic then shows a pump on each manifold feed pipe after the low loss header. These pumps I am trying to common up into one pump and I'll need to balance the valves at the manifolds to achieve this. I reminded myself of the no actuators thread earlier and it's a good one. I think I'll be trying to do something like that , keeping the overall flow the constant and varying the flow temperature

I'm going with a slightly different setup to many by having a single circulation pump in the plant room rather than a pump on each manifold. I'll need to have a bypass in case all the valves suddenly close, but I presume the bypass is a pressure relief, so is normally closed and only opens when the pressure is too high and allows time for the pump to switch off. Flow Rate: We're installing an 11.2kW Ecodan. A major input to the pump sizing will be the dT flow to return which I'll assume is dT = 5C. Based on that I can work our a flow rate as F = P_Heat / (Heat_Capacity * dT) = 11.2kW / (4.2kJ/kg.K * 5K) = 0.47kg/s = 1.92m3/h. Pressure (Head): This comes down to the amount of pipe work you have and isn't a function of how high you house is (water goes up and back down). The flow rate dictates the resistance to flow which is the head. The main losses that came to mind were loop, at manifold and manifold feed: Loop: I've taken the longest loop and take that as a fraction of the overall loop length of the system and it works out as 6% (yes, I have a silly number of loops). That means it will have a flow rate of 6%*1.92m3/h = 0.12m3/h = 0.032kg/s. I don't have data for 16mm UFH pipe but 15mm Hep2O is probably a good proxy and they publish that. In other considerations I worked fitted a line to that data which gives Head_Loss_KPA_Per_M = 79.9*(FLOW_IN_KG_PER_S^1.76) = 0.187 kPa/m. My longest loop is 110m long so that works out as a pressure drop across the loop of 110m * 0.15kPa/m = 20.6kPa = 2.1m head loss. At Manifold: due to valving etc: Guestimated as 1m head loss. I expect/hope this is an overestimate but would depend on how we have the balancing valves set etc. Manifold feed: I've taken the manifold with the most loops which is also the furthest on it and take that as a fraction of the overall loop length of the system and it works out as 48%. That means it will have a flow rate of 48%*1.92m3/h = 0.92m3/h = 0.256kg/s. For 28mm Hep2O Head_Loss_KPA_Per_M = 2.89*(FLOW_IN_KG_PER_S^1.76) = 0.263 kPa/m. This manifold is 36m round trip from the plant room (difficult routing) so that works out as a pressure drop across manifold feed and return 36m * 0.21kPa/m = 9.5kPa = 0.95m head loss. The sum of those three head losses is 2.1m + 1m + 0.95m = 4.05m. There will likely be other losses, but hopefully the 'at manifold' figure is pessimistic. I think conventional wisdom is to go with 6m of head loss capability. A Grundfos UPS2 25/80 (180) should work. The 25 number represents the fitting diameter, 80 represents the maximum head (in kPa) so 8m, and the 180 is the distance between fittings. Operating at 4m head and ~2m3/h should give an efficiency of around 45% which whilst not peak is near. That pump is more powerful and expensive (twice) than a Lowara ECOCIRC L 25-8/180. That pump doesn't have efficiency data though. Oversizing the pump (e.g. Grundfos Magna1 32/80 (180) not shown below) could push it lower of its efficiency curve. Grundfos UPS2 25/80 (180): Lowara ECOCIRC L 25-8/180:

I can happily do that for the DHW 15mm and 10mm pipes, but the void is too cramped for 19mm insulation on 28mm pipe unfortunately.

Below is a table from BS 5422:2009 which assumes 60C pipe and 15C ambient. Looking at 28mm pipe it has a minimum thickness of 16mm for 0.035 W/m.K which is the best you can hope for from PE and 20mm for 0.040 W/m.K which is perhaps more realistic. At a 35C average flow/return temperature moving from PE13 to PE20 reduces the loss per metre by 20% from 3.8 W/m to 3.1 W/m, but both are massively under the maximum permissible heat loss of 10.07 W/m.

@Nickfromwales I'm going to route my UFH feed and return pipes through the ceiling void (~60mm high) to the manifolds. Flow temperatures are expected to be around 35C. Am I reading part L correctly that I wouldn't be able to use the 'standard' 13mm PE insulation the likes of Screwfix sell? With a low flow temperature, it doesn't make sense on paper to use phenolic, or 20mm thick PE. Appears that the regs disagree though.

Need to check building regs, but insulation looks mandatory: https://www.nhbc.co.uk/binaries/content/assets/nhbc/tech-zone/nhbc-standards/tech-guidance/8.1/pipeinsulation.pdf Part L: What's draconian is the insistence on using 60C for the consideration. PE needs to be much thicker than Phenolic for he same loss so that 10mm figure rises to around 20mm for PE.

I've got three manifolds: 2.5m, 8m and 15m from the low loss header. Doubling as flow and return gives a total of 5+16+30=51m. I pessimistically rounded up to 60m. Payback times should be independent of length in this calculation.

On another thread I think I worked out that there is little point in insulating domestic hot water pipes unless you have a circulatory system. Cold water pipes should be insulated to avoid condensation. I've been wondering about UFH manifold feed and return pipes and did some calculations I thought were worth sharing: I adapted the pipe insulation spreadsheet from the CheGuide.com. The table shows the amount of heat lost in the feed/return pipes. 'Recovery Factor' represents the usefulness of heat that is lost since it isn't truly lost, it is staying within the heated envelope, but in the wrong place. I intend to have a relatively uniform heat and so most of the heat will be 'recovered'. Various insulation scenarios are considered with the resulting annual cost of lost heat as well as the cost of the insulation (material only). The payback time for insulating PE 13 (e.g. ScrewFix) is just 3.4years. The payback time of upgrading from PE 13 to Phenolic 15 Shiny (e.g. Kooltherm) is 38years. That ignores interest/inflation. There is no consideration of the carbon costs, either of lost heat or insulation manufacture. 'Cost of heat' is based on £0.30/kWh electricity an a COP of 300% which is hopefully pessimistic, but who knows these days. Not everything comes down to cost obviously, but using 13mm PE insulation looks to offer the best compromise for my system based on a relatively low 35C average flow/return temperature (e.g. 38C flow, 32C return). I hope to have lower temperatures than that, in which case the payback times go up higher. If however you run your ASHP flow temperatures at 65C, the payback time of upgrading to Phenolic 15 Shiny would be about 13 years.

With 12.5mm PB, I'd use battens at 400mm centres. Minimal extra cost/weight/time.

There are some expensive profiles out there to do this. First link has an installation animation. ~£35/m seems steep to me, but may be the easiest way to go. https://www.darklightdesign.com/led-profilelement-dsl-profile/ https://www.ebay.co.uk/itm/273214350882 https://www.iluminize.com/en/shop/product/4604-led-drywall-profile-dsl-2m-long-for-floating-surfaces-with-a-substructure-363#attr=

Is the loft living space? If it is, and the house is 3 storey, you will need this ceiling to be fire rated. That shouldn't rule out the battens, but you'll need to something neat with plasterboard (PB) to achieve a fire seal. Lots of strips of PB probably. Also check the fire properties of the LED strips as they may have a minimum distance to timber. PB in the way should solve that though. Something like the image below. If the plasterboard was 12.5mm then you could use 50mm x 38mm battens at 400mm c/c. If using thicker or thinner plasterboard, you could change batten thickness accordingly. Plasterboard strips can be screwed through with long PB screws, ensuring at least 25mm into timber. Also through the bottom most sheet and through the strips. Use a continuous bead of FireStop sealant between strips. You would probably want to use a plasterboard edge bead. No idea if this would meet regs, so you'll need to check that. Is there any indication as to how big the gap dimensions need to be.

I was planning to use a tanking kit in the shower but not the rest of the room (e.g. not near bath).

Wife is full of opinions but not decisions so probably makes sense to S&C. Also, not a fan of D&D.

Good question. Not given much thought but intended to use waterproof tile adhesive and waterproof grout. Any recommendations?

Tile thickness may be a factor. If putting onto plaster the tiles sit further forward. One room has a mix of blockwork and plasterboard. One is just blockwork.

In bathrooms I plan to have walls that are tiled up to a height and then plastered above that height. How should I approach this? Blockwork background. I can think of: 1. Bare blocks for tiling and put a batten or something on the wall and plasterer comes down to that 2. HardWall and MultiFinish plaster & skim whole area and tile in top 3. Sand&Cement plaster whole area and skim down to a line. Tile over bare S&C plaster 4. Tile bare blockwork before plastering 5. Something I haven't thought of 🙂

For bedding slabs I think you want sharp sand (check though) and I don't think your 3mm grit will fair well. I would get the bag swapped. The BM may charge a delivery charge, but you should be able to return the grit. Unless of course you can think of something else to do with the grit. I don't know much about laying paving, but was surprised when I learnt how thick the bedding mortar should be. Something like 40mm if I recall correctly. Below is a video I have watched before on this. Don't forget the slope away from the house.

Here's another picture The pillar is one stretcher wide plus plaster

I hope that's a joke. These are engineering bricks so shouldn't have much salt in them should they. They will be very low porosity so wouldn't it be unlikely to be coming from the bricks. The first picture is about 3cm x 3cm total area, so the salt itself is about the size of a small fingernail.

Plasterer finished plastering upstairs a week ago and will come back in a month or more to do downstairs. Happy with everything. One thing I have noticed though is some salt on the surface of the plaster. Only on a couple of engineering brick pillars which are between windows. Is this because the only path for the water to leave has been via evaporation at the plaster's surface rather than via being sucked into the blockwork like elsewhere? Make up is Knauf MR plasterboard stuck to reveal with Knauf plasterboard adhesive and primed with BG BondIt. Plastered with BG HardWall and then BG MultiFinish skim. I expect would have had Webber pink mesh here. Catnic corner beads. Possible Bonding Coat was used on the Engineering Bricks, I can't remember. It could be the water from both the plaster and the plasterboard adhesive has had to exit via this small area. Only noticed it today (June 13). Probably plastered end of May. Been very hot for last week, though only risen to ~22C inside. Haven't been in room much so no reason to have noticed sooner. @nod is this normal?

A middle ground is a single 15mm layer of Soundbloc (12.6kg/m2) or Soundbloc F (14.1kg/m2). I started a thread when I was trying to understand a lot of PB stuff. Don't forget to add the weight of a 2 - 3mm MultiFinish skim which is 3.4 - 5kg/m2 unless you plane to tape and joint.

I'm envious of how tidy you site looks. Mine is a tip as I have materials everywhere. Be it inflation, lack of availability or tiles made in Ukraine I've ended up not getting things as needed but as possible. Annoying as it gets in the way.

I saw a US video that said pre pandemic 1/2" 8x4 sheets of OSB were $8. That's £6! I doubt we had that in the UK though. Can remember a Chippie suggesting £1/m for 4x2 in about 2019. In 2020 I was happy with £1/mm thickness for basic plywood 8x4.

I wonder if they deliver down to Cambridge🤣

Says it's damaged stock