Ian

Product directory - MCS (mcscertified.com)

Gen6 SCOPs:

New HT SCOPS:

@hughf thanks, I had been zeroing in on daikin as a likely candidate as those DT settings are indeed there in the manual, and I find it one of the better written manuals. annoying that the new samsung still doesn't have a published set of manuals yet.

I really appreciate the help, any of you guys fancy installing a system in milton keynes? I'm really struggling to find an installer that I'm comfortable to give the work to. Met plenty of "plumbers" who know less about heat engineering than I do (but are far better pipework fitters) and so run away once a conversation about system design is initiated...

PWM pumps, I've been wanting to change my heat-only gas boiler's pump (grundfos alpha2) to a PWM one for ages. at fixed max speed it heats the house but is really noisy , and when demand is low the pipes resonate due to the TRV small openings. in PP3 mode its super quiet but not enough flow for the whole house on a cold day. I do manual PWM by running up there and pressing the button if its below zero...:(. I have the means of generating a PWM control signal based on heating load - evohome radiator heads running into home-assistant through ramses-RF gives me the number for % heat demand for the house (and/or for every single room) which can be mapped to a PWM level, an ESP32 board will do the hardware part - but tracking down a PWM pump (with control cable) in the uk domestic market is proving challenging for me (as far as I can tell the commonly available grundfos UPS3 is PWM capable, but no-one uses or sells the PWM parts in the UK...)

 cheers

Ian

Just Google 'pwm cable for grundfos pumps' and you will find a selection of suitable cables on offer.

You could even just jam 3 crimp connectors in there if you can’t get a cable.

@hughf thanks, I had been zeroing in on daikin as a likely candidate as those DT settings are indeed there in the manual, and I find it one of the better written manuals. annoying that the new samsung still doesn't have a published set of manuals yet.

I really appreciate the help, any of you guys fancy installing a system in milton keynes? I'm really struggling to find an installer that I'm comfortable to give the work to. Met plenty of "plumbers" who know less about heat engineering than I do (but are far better pipework fitters) and so run away once a conversation about system design is initiated...

PWM pumps, I've been wanting to change my heat-only gas boiler's pump (grundfos alpha2) to a PWM one for ages. at fixed max speed it heats the house but is really noisy , and when demand is low the pipes resonate due to the TRV small openings. in PP3 mode its super quiet but not enough flow for the whole house on a cold day. I do manual PWM by running up there and pressing the button if its below zero...:(. I have the means of generating a PWM control signal based on heating load - evohome radiator heads running into home-assistant through ramses-RF gives me the number for % heat demand for the house (and/or for every single room) which can be mapped to a PWM level, an ESP32 board will do the hardware part - but tracking down a PWM pump (with control cable) in the uk domestic market is proving challenging for me (as far as I can tell the commonly available grundfos UPS3 is PWM capable, but no-one uses or sells the PWM parts in the UK...)

 cheers

Ian

I need to check the manual to see if that’s adjustable.

Daikin altherma also supports a choice of target delta-T settings, one for rads, one for  FCUs, one for ufh.

Samsung gen5 has always supported a pwm primary pump, it’s just that the only instructions that mentioned using one were those from midsummer wholesale. And as the Samsung needs an external pump, and most plumbers are idiots, asking them to wire up another cable to a pump is too much complexity. As a result, most Samsung installs are with a fixed speed primary pump. 

Heat pump performance is influenced more on how you control the flow and return temperatures more than how the refrigerant circuit is configured, most use similar gasses, compressors, expansion valves and heat exchangers, therefore have similar performance.

I have done sone very interesting research on system configuration and performance, it really is surprising how system configuration and operation affects performance. Mars has alluded to it a while ago, and I will be publishing it here shortly.

The jury is out on the New Samsung unit, until I have seen some actual performance figures, in our climate and understand the control strategy, I will not comment on it regardless of what anyone says.

whereas a wider DT of just 7 drops the flow rate needed to 28.4 l/min and it becomes feasible in 28mm copper, and the nuance that I'm considering to split it into 4x 28mm plastic  (2 per direction, half the flow rate per leg) to go through the "wiggly under roof valley shortcut" currently used by the boiler primary (which is in 2x 28mm plastic), becomes feasible as well, and all of a sudden it becomes quite do-able..

@iancalderbank. In a recent post @heacol stated that the ideal DT is 8 degrees C, so it may be worth asking him if the Panasonic heat pumps that he fits are set to this DT and whether the flow rates are reduced as a result.