@william1066 I too am looking at the zone valves question for a 14kw direct DIY build I'm planning. rapidly concluding honeywells are a really bad idea. I know I have less than good enough for heat pump flow rate in some areas of my existing setup, trying to work through which bits of it need rebuilding. Discovered a 15mm (just to make it worse - plastic) 🙁 driving 3 downstairs rads yesterday... draindown coming (when the weather warms up a bit)

anyway this may help you : ?

bellimo3025 (I assume thats the size @heacol uses) https://www.belimo.com/uk/shop/en_GB/Valves/Ball-Valves/R3025-BL2/p?code=R3025-BL2 => to get the valve spec => kvs 10m3/h

Can't find the esbe ones anywhere.

but this may do the trick:  not one of his mentioned brands but available and a good price, another italian make., . https://midsummerwholesale.co.uk/buy/renewable-heat-accessories/mut-meccanica-tovo-sv-3-port-valve.    Good claimed kvs of 12.6m3/h.

but this may do the trick:  not one of his mentioned brands but available and a good price, another italian make., . https://midsummerwholesale.co.uk/buy/renewable-heat-accessories/mut-meccanica-tovo-sv-3-port-valve.    Good claimed kvs of 12.6m3/h.

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That valve is not suitable, the KV value is false, I have just thrown on in the bin from a brand-new installation. Here is the link to the belimo valve, I do not use the ESBE valve.

https://www.jtmplumbing.co.uk/central-heating-controls-valves-c436/belimo-valves-actuators-c1014/belimo-valves-c408/belimo-3-port-zone-valve-with-240v-actuator-powered-open-powered-close-p26349

Unfortunately, the 1"version is not currently in stock (I think I bought them all 🙂  ) If you can wait a another couple of weeks, we will be selling the best valve on the market.

@heacol thanks. those belimo's are pricey but I guess you pays your money and you takes your choice. I'm a few months away. so I can certainly wait. What do you use for a 2 port? R2025-S2-LRF230 ? as I understand it best practice for non-glycol install is antifreeze valves outside, 2 port valves just inside the house one each on F+R? so 1x 3 port for CH/DHW diversion plus 2x 2 port for the AFV's starting to add up, £688  inc vat to do it with quality kit.

@iancalderbank I do not use 2 port, I only use full bore 3 port diverting valves. There is no reason, in any installation, to install 2 port valves. If you want your heat pump to work properly, it must be installed properly. If you cut corners and cost, you will pay tenfold or more in your bill.

@iancalderbank The way I read the chart is that to get 30 lpm you will lose 4 mh2o across the biggest valve in that list, that is quite a lot.  I am about the rip out all my zone valves and my mag filter in line with what Brendon suggested.  While I can get 30 lpm with my current setup, pump is consuming 128 watts and creating 10 mh2o pressure.  The noise of the pump is not great either. 

I also have a mag filter, which [I just discovered] has a specified max flow rate of 33 lpm, but no pressure charts I can find.  Given am losing about 2 mh2o on the pipes, 1 mh2o on the heat pump heat exchanger, and about 1 mh2o on the cylinder heat exchanger, that means the mag filter and my zone valve are probably consuming creating most of the other 6 mh2o in my circuit [when on DHW].  They are both coming out.

@william1066 Correct. Mag filters are not designed for high flow, they have between 4 and 6 right angle bends inside, and the friction loss is huge.

Posted by: @heacol

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@iancalderbank I do not use 2 port, I only use full bore 3 port diverting valves. There is no reason, in any installation, to install 2 port valves. If you want your heat pump to work properly, it must be installed properly. If you cut corners and cost, you will pay tenfold or more in your bill.

@heacol I'm not trying to cut corners or cost. The opposite. I'm trying to spec it right. I'm absolutely going to use a 3 port full bore for CH/DHW diversion. Probably one of the ones that you've cornered the market in 😉

In addition to this, its my understanding as part of freeze protection, that 2 port zone valves are required where the pipes come in to the property, to shutoff the outside pipework from the inside pipe work if the antifreeze valves open. Is my understanding incorrect?

@iancalderbank I am not accusing you for cutting corners, but if you have Honeywell type valves, someone has.

The correct valves are very difficult to find, as so few installers design systems for optimum flow. We are, however, going to rectify this problem and will be brining in hundreds of them.

If there is no-were for air to come in, water will not escape, it is just an excuse to use bad valves.

@heacol thanks, my bad , I missed giving you the most significant point . I have a gas boiler system at present with honeywell valves. I'm preparing my heat pump design for self install (similar setup to @william1066 ) hence very keen to get the right valve components up front. If you're going to import bellimo by the hundred thats brilliant.   so my point about  zone valves at the property entry point  for the freeze-protection is a design one, not a "current situation" one. If those were done with bellimo 2 ports I assume you'd not object (not on flow rate grounds at least), but , if I understand you correctly, you believe that zone valves at this point are unnecessary?

@heacol Hi Brendon - Do you have any experience with this filter?  That is my current choice for replacement of existing one. At 45 lpm is 1 mh2o.

@william1066 a hopefully not entirely bonkers thought if 1mh2o is too much .

Buy 2 and parallel them up. At half the flow each, about 0.15mh2o. They're not expensive.

@iancalderbank What about oxygen ingress.  I have tried to keep plastic out of the system as far as possible.  Right now, only the Sika flow meter is plastic.  The UFH has an AL layer. 

Maybe the amount of plastic is minimal, thoughts?