Posted by: @iancalderbank

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anything particular for the ESBE versus that one?

It looks a lot smaller, esp the actuator, and I have one of their mixing valves picked up off ebay, quite like it.

Specs for the VRG330 below (the blue line is not mine, but the example in the documentation)  I am going for max 1 lps so would be 0.4 mh20 on heating circuit and 1.1 mh20 when on dhw circuit.  (If I understand the diagram correctly).  But I am open to any other good options.

@william1066 I think you've misread the diagram. you read across at 1 l/sec and select any kvs line within the shaded area. My purple line.

higher kvs = bigger valve = lower DP.

so if you can use the valve with Kvs of 10 -> 12 kPa, up to the valve with kvs of 20 -> 3kPa. 

there's no difference in the valve's loss whether its on heating or hot water  - because  thats just divert left or right. I agree though the VRG33x series appear to not exist in the UK.

The VRG13x's do exist and are not a bad price. but the actuators seem rare and expensive. the 130 graph is here and is not significantly different to the 330.

so at 1 l/sec you'd be at 12kpa for kvs 10 (same as 130) and 5pka for kvs16. 

12kpa / 1.2mh20 may well be too much for you, but is 1 l/sec not an overkill for design target? thats 3.6m/3 h. by my maths, for 16kw @ DT5, you're aiming for 0.75 l/sec? my green line. which is 6 kPA = 0.6mh20, with a kvs10 VRG 133, which is a DN25 valve available in 28mm comp. the kvs16 is a DN32 1 1/4" one (yes, that size again).

https://www.jtmplumbing.co.uk/central-heating-controls-valves-c436/esbe-valves-c1287/esbe-valves-vrg133-mixing-valve-compression-fitting-p19111/s20699

but the esbe actuators are still  **** expensive in uk

https://www.jtmplumbing.co.uk/central-heating-controls-valves-c436/esbe-valves-c1287/esbe-valves-actuators-ara600-3-point-230v-ac-p28411

loads cheaper on ebay from germany...

out of interest, related question to help me: what resistance do you have in your mfr spec sheet for your cylinder's coil? I've just looked mine up and it said 0.6 bar = 6m h2o 🙁  !!! so I'm hoping its a misprint - it is a heat pump spec cylinder.

Ian

Posted by: @iancalderbank

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there's no difference in the valve's loss whether its on heating or hot water

It seems so, this diagram to a while to decipher.

Posted by: @iancalderbank

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but is 1 l/sec not an overkill for design target?

Heat Geek Towers runs at about 0.8 lps, the max for the 16kW samsung is 58 lpm.

This is the heat exchanger in the heat pump - specs

My Hot Water Cylinder heat exchanger i external, I don't use the coil in the cylinder.  I can get over 14kW transferred to the hot water at certain temperatures.  I don't know the pressure drop across it, and probably should have gone for a bigger one (surface area seems to be ok, but it has 3/4 connectors), but at the time of selection, I did not know enough.  In hindsight I probably should have gone for the NORDIC Ba-32-80 1" but was just copying what mixergy were doing and finding one that looked the same.

In any case my data (below) suggests I don't have too much of an issue there with surface area.

@william1066 ah ok your not using a cylinder coil. ok no worries. I just did the maths a different way - to get 6.5m head loss with a 28mm pipe based cylinder coil, that'd imply it had to be 100m long, which is clearly unfeasible for to fit inside a 300L cylinder, so surely it must be a misprint by my manufacturer (I hope!).

yes I forget its a mixing valve so straight through is an option in which case lower DP than turn right. was working on the diverter valve plumbing principle of in at the bottom then turn left for CH right for HW (or vice versa) in which case both would be on the "circle" line in the graph. whereas you can indeed get better DP by going straight on triangle/square route.

I still think its overkill though. as you say the the heatgeeks are at 0.8.  58lpm is indeed as near 1l/sec as makes no difference but that implies a DT of 4 at 16kw, do you really need to size it the valve that big for that low a DT and flowrate?

@heacol where are your new valves coming?

Posted by: @iancalderbank

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@william1066 ah ok your not using a cylinder coil. ok no worries. I just did the maths a different way - to get 6.5m head loss with a 28mm pipe based cylinder coil, that'd imply it had to be 100m long, which is clearly unfeasible for to fit inside a 300L cylinder, so surely it must be a misprint by my manufacturer (I hope!).

yes I forget its a mixing valve so straight through is an option in which case lower DP than turn right. was working on the diverter valve plumbing principle of in at the bottom then turn left for CH right for HW (or vice versa) in which case both would be on the "circle" line in the graph. whereas you can indeed get better DP by going straight on triangle/square route.

I still think its overkill though. as you say the the heatgeeks are at 0.8.  58lpm is indeed as near 1l/sec as makes no difference but that implies a DT of 4 at 16kw, do you really need to size it the valve that big for that low a DT and flowrate?

@heacol where are your new valves coming?

I'm afraid that if I had a heat loss of 16kW per hour, I would be concentrating much more effort on lowering my heat loss than meeting it.

Posted by: @derek-m

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I'm afraid that if I had a heat loss of 16kW per hour, I would be concentrating much more effort on lowering my heat loss than meeting it.

Indeed, that would be wise, my situation is complicated [you don't want to know 😀]

TLDR version - oil boiler died - bought heat pump - heat pump installed by 24th December ( [just] in time for Christmas) - renovations in progress -  50 sqm of 170 sqm converted to UFH so far. 

In any case the heat exchanger is a retrofit to my thermal store that does not have enough coil in it for a heat pump.  All of heating system is water + anti freeze valves (no glycol)

Posted by: @iancalderbank

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 do you really need to size it the valve that big for that low a DT and flowrate?

This is mostly a vanity exercise in CoP, so not not strictly needed, but good to have the option to explore the limits of CoP.  Once we are finished the renovations we will have moved from 15kW down to 11kW @ -2 degC and I may have a heat pump that is too big.

What is interesting about the 16kW Samsung Gen6 vs 12kW is that it is seems to have exactly the same construction (same flow rate, same quantity of refrigerants, same weight [1% delta], exactly the same dimensions)  as the 12kW.  The main differences are air flow rate, noise and power consumption.

was just studying the bellimo manuals, I'm not sure that the 3025 is the right valve. this says its for 2 in 1 out, not 1 in 2 out. explicitly says don't run it the other way.

whereas I think for 1 in 2 out, this might be the right one C325Q-J  and with actuator it looks like this which is a bit smaller

What is interesting about the 16kW Samsung Gen6 vs 12kW is that it is seems to have exactly the same construction (same flow rate, same quantity of refrigerants, same weight [1% delta], exactly the same dimensions)  as the 12kW.  The main differences are air flow rate, noise and power consumption.

 

I have read somewhere they are the same unit. just software.

@iancalderbank In the end I have gone for the VRG133 and ARA645. the 645 switches in 30 seconds, which I am fine with. So just need to decide on the filter, then need to wait for a warm[er] weekend to fit the lot.

Also having fun and games with the PWM.  While I saw the samsung manual mentioned PWM I was confused since, the instructions from the supplier of the heatpump did not mention this at all and did not spec a PWM pump - very dissapointing ...  In any case, I ended up with a second hand pump that takes a 0-10v signal so now have  a PWM -> 0-10v -> 10-0v  setup.  Not ideal, but don't want to get rid of my pump which does modbus.

In hindsight should have gone with the UPMM pump.

Looking forward to seeing what the Samsung controller actually does when it can control flow speed and has the full range of 12-58 lpm.  Other commentary suggests the controller does nothing, this effort and expense may all be in vain.

@william1066 where did you decide to get the vrg133/ara645 from if you don't mind me asking? not had much luck finding the actuators at reasonable pricing.

PWM, yes thats a pain. I had a good look at the Magnas last week, they have some nice features, but the absence of PWM on that pump is peculiar, maybe its not a thing in industrial / commercial situations. If you're having to invert 0-10 into 10-0 as well thats even more of a faff. midsummer are saying UPMM out of stock right now. 

interestingly I did the samsung installer course earlier this week, PWM was mentioned purely in the context of how to wire it up, but at least it was there. there was no discussion about optimisation at all.  what it did say, in black and white, was the 16kw needs 46lpm. not 58.  pm me an email for more info.

Posted by: @iancalderbank

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where did you decide to get the vrg133/ara645 from if you don't mind me asking?

ebay, is where I source the stuff difficult to get or expensive in UK.