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...And I realise now that I basically re-iterated what @Ferdinand said in his earlier post

Yes but I expect the dT is something like 8c based on 45/37 which is the hot end and traditional flows. It is also designed to get the room temperatures up within 60 minutes from memory - there is a set of parameters hidden somewhere and you can alter these. If you’re using ASHP as a heat source then you really want to be using E7 and overnight - slab on at 3:30am to absorb low grade heat for 3 hours etc. That needs a lower flow temp and closer to the final room / slab temp you’re looking for so ideally it’s nearer the 35c flow (most ASHP have 35c as optimum for CoP) blended with the return water. Ignore that entirely !! That’s the flow the ASHP needs, not the floor. The floor flow is set by the manifold circulation pump, not the ASHP pump and it’s a bad idea to just connect the ASHP to the manifold and hope it runs ok as the zones closing will play havoc with the flow. I’d use a small buffer - 60-100litre - and let this do the balancing to the ASHP. The heat pump then uses the tank stat on the buffer to fire rather than the call for heat from the UFH controller as it is less likely to short cycle or find flow restricted.

Exactly right. And that's what hooked my interest. Because doing that isn't easy. Snatched moments reading here and there point to hints that may help answer your questions. My aim is to beat @Ferdinand to a well argued answer for you. You up for that F?

I know. It's crazy. The problem is putting all private planning matters under one umbrella labelled 'problem'. I am labouring, rightly or wrongly, under the belief that a house should not put the average person under a lifetime of debt.

I use recycled aggregate Medium density blocks

Probably teaching to suck eggs, however it is often necessary to do some manual untangling before cutting ivy stems as they become very well attached over time.

Someone needs a Dutchman ...

Thinking about the physics of this a bit more, it might be a good idea to contact your preferred lift vendor and get a base spec.from them as the required strength could vary a lot depending on the design of the posts: if they have biggish "spreaders" to distribute the force then the torque on the mounting from an unbalanced load will be a lot less than if say it's just a 500mm square plate, and the requirements for your base will follow. By friend Big Nick had one installed a few years back and the first thing the guy did was to drill some test holes in various places in his workshop floor. He wouldn't install it where Nick really wanted as there was only 5 or 6" thickness concrete there, and so it got put somewhere else where there was 10...11" IIRC. FYI, the 200mm figure Tony gave me was based on a 6m x 12m slab and being able to carry/work on a small van.

You are correct. As in Here be Dragons. What an interesting question. You have me hooked. To help unravel this type of complex problem I always resort to Martin Goodhalls blog. No guarantee of a definitive answer but always interesting, always evidence based. What more can a boy need? This link is a search to mentions of the term derelict in his blog Just found this .... in farminguk.com

One thing to watch is that driven rain runs down the door and easily gets underneath it, in our last house, they didn't put a run on the area under the door so water ran under the door and into the garage. I don't think the door closing into a slot is a good idea as it would fill up with water. Looking at your picture, why not run the flagstone just under the door above the Fibran, putting a slight run on it so the water runs away from the door. Then cut a 20mm wide channel in the screed behind the door (or put an edge there when you screed the floor) this way the flagstone will not touch the screed. As the channel is inside, it wouldn't need covered, you can just drive over it. You might want to cover it to avoid it filling up with dirt or rain when the door is open however. Garage_Threshold1.pdf

Stick to one manifold. As long as the runs are 100m or less you’ll be perfectly ok. As peter says, ask Wunda for the auto balancing actuators and you don’t need to do any commissioning whatsoever. Just plug and play, and go to the pub. Where the pipes are congested, just insulate the flows and leave the returns bare. If you’re on an ASHP then stick to 150mm centres to keep the water volume high.

What’s the Delta- T and output temperature they have designed it to ..?? Screed depth and material..?? 150mm is quite tight for some of those loops - I would look at 200mm centres and run it lower temperature for longer. Like others - need it in the En-suites and a lot to be gained from using the individual flow and return pipes in hallways etc. Loop lengths are irrelevant, they should be roughly equal where heating the same room, but use the auto balancing actuators and 99% of the problems go away.

Nice outcome. It is fairly common to see applications to have conditions varied or removed. Feel free not to reply but I would be interested to know how much were the fees for the planning consultants?

We all like different things, I have deliberately never put up my floor plans as I know some people wouldn’t like them, so what I’m building it for me not them. If you like your lindab gutters then that’s great. I personally don’t it’s not that you have crap taste, just different to me.

FWIW, I didn't risk having the manifold splattered with concrete (and didn't want it sat outside anyway), so we just left the pipes too long, capped them, and tied them to a timber frame poking up out of the slab.

The Salus actuators don't care about the direction, they just try to establish a temperature differential between the two (unmarked) sensors. The temperature differential they aim for depends on the flow temperature, so if this is less than 30°C the valve will aim to get a 4°C differential, if the flow temperature is over 30°C then the actuator will try to maintain a 7°C differential. So, when in cooling mode the actuator tries to maintain a 4°C temperature differential between flow and return, which seems to be OK (it's the same differential as it tries to maintain in heating mode for us). The manifold TMV just fully opens, as it tries to get the manifold temperature up to the set value and can't, so it stays wide open. The manifold temperature in cooling mode is then determined by the ASHP set temperature.

I run my supply temp at 15C. I get a breath of condensation on the manifold - never any droplets. I came in having been out for a bit this afternoon and it was like bloody heaven walking in the front door. Can't recommend it highly enough.

Thanks Conor. The first quote I've had works out at about £135/m2 but doesn't include hardcore, binding, DPM/tanking. The insualtion itself is being quoted at £65/m2 for 'passivehaus standard'. Give me a shout with any alternatives who travel, if you can!

I noticed that as well. There are lots of different perfectly valid installation approaches. Lots of debates about the advantages and disadvantages of S vs Y plan, though for an installation of this size, I would have expected S plan. SY plan if such a thing exists is just bizarre, and smacks as if the installer doesn't really know what he or she is doing, IMO. A Y plan value in this configuration is just plain wrong, IMO. Surely you don't want a preference setup on this system as the boiler could drive both; this needs replaced by standard S plan.

They do come in different shapes and sizes, but all do the same thing, they ensure that the UFH runs at the set temperature, irrespective of the heat source temperature. Yours may be a smaller three port blender valve, with a smaller control. I've not seen a UFH manifold without a form of temperature control valve, either a two port one like ours, or a three port one. The three port ones look very much like the ones used on thermal stores or other hot water storage systems to control the DHW temperature. The UFH flow temperature needs to be adjusted to give just enough heat to the floor to warm the house quickly enough, without too much overshoot, just for comfort. Having a high UFH flow temperature tends to result in greater swings between the maximum and minimum room temperature, as it takes time for the heat to get from the UFH pipes to the floor surface, so if the UFH pipes are running too hot, the heat will continue to soak out to the floor for a long time after the thermostat has turned the heating off, resulting in the rooms continuing to warm up for some time. We suffer from this if the flow temperature exceeds about 26 deg C; as long as I keep the thermostatic valve set down below that level things are fine. The ASHP flow temperature, just like any other heat source, needs to be set to give best performance at the load it is operating at. Running an ASHP at too cool a flow temp will tend to cause the unit to modulate down to a low level, all the time, and never operate at it's most efficient temperature. One key point is to get the difference between the flow and return temperature of the ASHP up to a reasonable level, as this sets the modulation level and also has a significant impact on the anti-short cycle timing. If the ASHP is running with the anti-short cycle system kicking in a lot, then it's efficiency will drop because of all the additional starts and stops, especially in milder weather, when the heating isn't being required to deliver much heat.

I'm a bit puzzled. We run our UFH with a flow temp of around 25 to 26 deg C, but run the ASHP flow at a fixed 40 deg C, as that seems to give the best COP in practice. So, why couldn't the Panasonic Air Rad have been plumbed directly across the ASHP flow and return?

In my garage, I want all the Pirelli calendars ever made.