Plumbing design newbies basics

[Chablais]

So I have stripped out all the existing pipework, back to the incoming main, on my major renovation extension. I have an overall concept of what I am trying to do gleaned from reading this forum, but have many questions! Trying to make sure I am on the right track before buying all the kit.

I have three bedrooms all with ensuite WC, basin and shower, one has a bath. Heating is UFH on ground and lower ground floor, radiator in each bedroom, and towel rail/radiator in each ensuite/bathroom. Downstairs also has a bathroom with shower, WC, basin.

I have mains gas. so the concept is to have a new gas system boiler, an unvented cylinder and run UFH, heating and hot water, all from the tank.  Is this how it works?  The tank I am looking at is from AVChttps://www.acv.com/gb/professional/new_product/06627401-465/smart-e-plus-240#tabspace=unit&tabid=diagrams,  and is a tank in tank system, so using the primary heating water as a buffer for the UFH and radiators. Using Hep20 from a manifold for hot and cold water, and run the upstairs radiators from another manifold upstairs. 

I know I need a double check valve and stop cock on the incoming main, and a PRV before the tank, the tank comes with a mixer valve. After that I am not sure what I need

I have seen some on here use one large, valved, brass Hep20 manifold say in the utility room next to the boiler and tank, to feed everything, others have used sub manifolds for each room, using the much cheaper, plastic, non valved Hep20 manifolds. Is this purely to save money, I like the idea of being able to turn off individual consumers from the manifold, but unsure in real life how often this could happen, cost difference is considerable, but then it is a one off cost.

Control wise I am planning on using Heatmiser Neo thermostats on each zone, and a Neohub and their wiring centre for the UFH and also for the radiator manifold circuits. Boiler was looking at Veissman Vitodan 200 series but unsure on sizing, these are available with weather compensation, but will this work with Heatmiser, how do they talk to each other? Was trying to find modulating thermostats but Heatmiser don't offer them. 

Also unsure on UVC sizing, as it appears I could run a smaller tank, 210 litres,  if I have a large enough output boiler to reheat it fast enough, or is it better to have a larger tank, 300 litres and a smaller boiler, also have a solar array of 3.7KW  so was hoping to use a diverter to an immersion in the tank for all excess solar.

I apologise for so many questions, but feeling a bit overwhelmed by everything. 

 

[PeterW]

If you haven’t already bought it, avoid that ACV like the plague as they are a nightmare to plumb in and really don’t work that well. 
 

Depending on air tightness and uValues you could go UVC but for 3 en-suites it will need to be 400 litres. Alternative is a thermal store that will also take your excess PV but both need good water pressure. Option on the UVC would be fit a small buffer tank too to keep the boiler condensing and not short cycling.  

[osmononame]

2 hours ago, PeterW said:

If you haven’t already bought it, avoid that ACV like the plague as they are a nightmare to plumb in and really don’t work that well. 
 

Depending on air tightness and uValues you could go UVC but for 3 en-suites it will need to be 400 litres. Alternative is a thermal store that will also take your excess PV but both need good water pressure. Option on the UVC would be fit a small buffer tank too to keep the boiler condensing and not short cycling.  

 

This is what we are hoping to do. A 300l uvc with a buffer tank for the ufh. We will be using gas as our primary source but will have a circa 4kw pv array so plan would be to divert that to uvc and buffer tank (if you can - I haven't seen any that have an immerser but not looked that hard).

[Chablais]

Hi Peter

 

I have not purchased a cylinder yet, only Hep20 pipe. What are the issues with plumbing the ACV cylinders? On the face of it they appear a good solution, fast reheat times, using the heating water as a buffer to feed the UFH. Also have an immersion elemnet to dump my solar. Can see they need filling/emptying in a defined sequence to stop the inner tank being deformed. Attached one of their schematics. 

We will be well insulated, and as airtight as we can. Not ready for airtest yet. Going to fit Hansgrohe Ecosmart showers as 9ltrs/min. What would you recommend if not the ACV? Thanks for your input, it is appreciated, thanks