PeterW

If that’s surface based pipe using the old 10mm stuff then it is about right - that was designed to work the same as a radiator in reality and just warm the air above. The newer systems use the heat capacity of the concrete to reduce the thermal “swing” and lessen the variations. @TerryE did some really nice modeling of his slab to show how it works.

Zoning rooms gets challenging, but zoning different floors and especially with different floor composition is essential.

You have to know the delta loss and the heat transfer of the floor build up. 33c would be fine in concrete but need longer running, 37c under wood and shorter run time.

Flow temperature has to be below 40c with a chipboard based floor and also depends on the finish above - some wood flooring and laminates have a maximum floor temperature. There is also a comfort factor, and the issue with overshooting the target temperature as the higher the flow temperature, the easier it is to get a continuous increase of room temperature once the flow is switched off.

Just reading back - you’ll struggle to stop the boiler cycling with no mixing valve as you need to ensure the water into the floor remains below 40c at most, which means your boiler won’t be condensing. You could put a single TMV on the hot output from the tank to blend down the water to a maximum. Quickest way to control the manifolds and flow temps are the Wunda Trade automates heads that regulate flow and return delta to 7c. Not cheap at about £14 each, but worth it. A tank stat will have enough hysteresis to cope with the on/off needs on the tank. Yes, it will run at 55c or so but it will also mean you get maximum efficiency from the boiler. How many manifolds are there ..? My only concern is where you have one set of circuits in screed and the other in timber as they will react very differently. I’m assuming you have multiple zones planned ..??

Ok - what are the plans for hot water ..?

Minimum one pump per manifold as it just won’t cut it otherwise. Why the rush to get heating on.? What stage are you at ..??

Don’t bother trying to find a 10mm pushfit manifold - just use a standard UFH one and a short leg of 16mm UFH pipe and then use a reducer or see if you can get a manifold with 15mm eurocones on it and 15/10 is an easy size to find in pushfit.

The plan itself ......?? ?

Now that’s an even worse idea ..!!!! Why use the PHE then..?? Just use the coil as the DHW heat ..! But it won’t be more than 6Kw so the showers will be crucified ... New balls please ...

I agree my old welsh wonder, but how many standard 140 litre tanks have you seen with multiple tappings..??? If you are planning to run UFH return, boiler flow and PHE return all through the same tapping then something will starve as you will have 2 positive and one negative head pumps all running against each other when the boiler is topping up and the UFH is running and a shower kicks in... You’ll spend more on cutting and fitting extra tappings than it’s worth, and the coil as heat makes the most sense as you remove the negative pressure source from the bottom tapping.... Or shall we have a lesson on fluid dynamics ...???

That assumes a perfect cylinder with a coil large enough to push the heat into the cylinder. That is not the case and it will probably take nearly twice as long to heat the cylinder.

6KVA can't be correct as that is about 30A. They also say its a 100A service fuse on the drawings..? 155m of laid cable doesn't sound too bad at £6000, that has got 2 major joints plus overhead and underground work. For reference, I was charged £1350 for 4m where I installed the ducting and this was in an unmade road so the reinstatement was zero...

They do - they just don't call it that !! Micro-rebar has a number of trade names over the pond, Helix being one of them. They are essentially stainless needles that get mixed into the concrete at the final mix, and are in certain circumstances a replacement for rebar. Over here, if you ask for fibre reinforced concrete then you may get either stainless needles or fibreglass needles in the mix. The key reason for it not being used as much in structural elements such as ICF is that you cannot guarantee the mix for strength purposes. For example, it is assumed that when you chuck 4 boxes of fibre into an 8 cubic metre concrete load, that they become evenly spread through the mix resulting in 1/2 box per cubic metre. If you analysed the concrete you may find this is far from the truth as they tend to bunch and thicken the mix slightly, so box 4 will not be as evenly mixed as box 1. With that being the case, you can't guarantee the strength and therefore the rebar has to stay. In a ground floor slab, not having a perfect distribution isn't an issue as long as its there or thereabouts. Now change that to a wall structure, and the cold joint between the two pours is virtually flat - there aren't 10,000 little fibres poking up so the mechanical jointing between the pours nears zero. Also, fibre reduces the flow characteristics of concrete so filling with fibre reinforced is more difficult.

As @ProDave says - thermal store needs to be bigger rather than smaller as it’s acting as not just your DHW buffer but your heating buffer too in this instance. I would bite the bullet and add in a much bigger TS, lose the PHE and pump as that’s just things to go wrong, and use an in tank coil. I would add a pair of immersions - one 1/3 up and one 2/3 up and use them to offset the PV or even use on E7 as backup. Other option is to add a second “solar coil” at the bottom of the TS and link to the ASHP and the UFH. - would give low grade heat to the tank from PV driven ASHP and you could divert this to the UFH for heating, and then isolate it for cooling.

The only way to actively cool is to lose the heat out of the building - easier said than done if you are keeping the heat inside the fabric and you’re also talking about wanting cooling when ambient air is +23/24c which is near impossible with a water source. With a 2kw ventilation heat loss, have you got MVHR in there ..?? If not, plan now as that could sort your 10% SAP saving in very quick order. If you are tight on capex then look at a big UVC and a buffer with a a coil in it - use a standard indirect hot water tank if needed and then hook a cheap ASHP to it which will allow you to cool the slab in summer but also if you add an immersion into that buffer it will allow you to use as a secondary dump for excess PV.

Do you have the boiler spec and the total heat loss requirements for the house..?? 140l isn’t going to cut it - sorry.... I’d be looking at 250 litre UVC at this point or potentially a pair of Sunamps however that is an expensive capital outlay and I’m not sure about your budget. Cooling with mains cold wont work - you’ll lose the inhibitor out of the system. A small cheap ASHP would help but it’s not going to help your SAP / DER score so I would suggest it’s left as an after build additional element. I would put a small buffer in the system to hydraulically separate the UFH and the cooling / heating sources.

With all due respect, which way up this lot is is entirely irrelevant as the pump not firing won’t actually change its behaviour as it’s based on pressure loss and that is the same regardless....

If you leave the boost on 5, the flap remains up so heat basically releases as it goes in hence the heat out during the heating period.

No.... they don’t .... They have power to enforce a material breach of planning, but given that has to be done through a court and they don’t have the money to do it - and lets be honest this is a minor infringement - then they will leave you alone. Build a 3 storey house where you have permission for a bungalow and stick dormers in the roof too, then you may expect a visit from the enforcement officer. Councils are too busy just doing the basics to worry about whether your temporary fence is in the right place or made of the right things.

May be worth giving Jackson’s Fencing a ring as they will probably be much keener on price than Jewsons.

I’ve fitted the upward units from DIY Kitchens and they don’t need the motor at all - perfectly balanced and very easily adjustable. Motors are just one more thing to go wrong ..!!

Sounds like the circulation pump has been fitted to run when the boiler runs which would be the same time as when you have hot water etc. Isn’t it a Robbens UFH system ..? Pretty sure they have a pump trigger off the main UFH board but wouldn’t know without the exact model. Have you got a schematic you can post ..? And the midlands isn’t far from South Wales ... ?

You’re getting hung up about nothing - there are bigger things to get stressed about. Stick the gravel boards on, then just clear the concrete where you can and carry on. In the meantime, remove their access rights without a specific appointment (see the @JSHarris letter template) and then just carry on ... Stop taking the victim position and just play the game with them..!

You may find the flow switch has the same size mag pellet as some of the others on the market or it can just be cut down and the cut down piece replaced with silicon rubber or plastic.