Posted by: @craig1980

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you are correct, I was just adding the info for Derek.

I'm adding the annotations for everyone else...

... especially those who will arrive at across this topic in the months and years to come 😉 

Annotations for Mike's system will magically appear here in a few minutes.

The annotations were brilliant and helped me too. I was talking about the water pump. Just to save any confusion. Thanks for your help so far. 

Mike H's set-up (details to follow pending any additional photos)

And here's the relevant installation diagram from the Grundfos manual for Pump-2

The idea is to keep the control box above the horizontal. If water leaks from the pump-body, it mustn't drip into the electronics.

I've looked on the World Heat website for details of the dumpy Ecotherm cylinder. The best match I can find is a 50-litre buffer vessel.

@transparent Thanks very much for the annotations and the pump info. Yes it is a 50 litre buffer vessel.

@derek-m I don't have a better photo at the moment as I'm away looking after grandkids.

Is varying pump speed one way of maintaining Delta T at around 5 degrees? If so, on which pump would the flow be altered - the one on the heat pump circuit or the one on the radiator circuit or both?

Posted by: @mike-h

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@transparent Thanks very much for the annotations and the pump info. Yes it is a 50 litre buffer vessel.

@derek-m I don't have a better photo at the moment as I'm away looking after grandkids.

Is varying pump speed one way of maintaining Delta T at around 5 degrees? If so, on which pump would the flow be altered - the one on the heat pump circuit or the one on the radiator circuit or both?

As far as I am aware, virtually all ASHP manufacturer's now fit a speed controlled water pump inside their system, except Samsung. There are two main ways in which the heat energy produced by a heat pump can be varied, one is to run the compressor harder, so that it increases the LWT, the other is to vary the water flow rate, so that it transfers more heat energy to the heat emitters. In most cases both methods are used to increase the range over which the heat energy output can be controlled.

In your case I suspect that the speed of the water pump is not being controlled, which is one of the reasons why the buffer tank has been installed.

To answer your question, it would be the primary pump that would be controlled to maintain the Delta T.

To obtain maximum efficiency in a system with a buffer tank, the water flow into the buffer, should match the water flow out of the buffer to the heat emitters. This of course will not be possible unless both water pumps are controlled, and can be adjusted to operate at the same flow rate.

I'm pretty sure that @mike-h 's Pump-2 is a UPS15-20 (or -30) which is the type most commonly used for domestic radiator circuits. It's likely to have a 3-stage rotary switch to select the flow-rate, and that's all.

The larger pump-1 could be the newer UPS2, but there are a number of variants, and we'll need the model number to know its features. I'm puzzled as to why it appears to have ribbing in the dyecast case. Very few domestic pumps from Grundfos have that.

Directly above it is a flow (& temperature?) sensor which might yield useful information if it has a name-plate which can be photographed.

I still struggle to see why Samsung are making a product that doesn't have a built in pump - nearly every other manufacturer has this all internal to the heatpump.

I've finally managed to download the Joule Samsung installation manual which details exactly how @Craig1980 's system is plumbed and wired. I've attached it for the benefit of the tape*

*excuse my humour...

And here are the original Samsung installation manual, and that from Midsummer wholesale, who specifically suggest improved performance can be obtained by using the Samsung controller as the room stat, and that  PWM pump can be connected to the control PCB inside the MIM (the metal box on the front of the cylinder)

@hughf that's interesting, thanks. Now, the controller thermostat reads higher than the room stats as it's in the airing cupboard with the uvc. Would that affect anything if I was to set it up as you say?

Posted by: @hughf

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and that  PWM pump can be connected to the control PCB inside the MIM

OK... so the point being made in the manual is that an 'ordinary' domestic central heating pump gets operated with a PWM signal, provided that it is connected into the Control PCB, rather than just being connected to 240v mains.

I have this arrangement for the Grundfos pump on my solar thermal array. For it to operate correctly on a pump with an inbuilt 3-speed selector (eg Grundfos UPS15-20), that selector must be left in the MAX speed position.

Posted by: @craig1980

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@hughf that's interesting, thanks. Now, the controller thermostat reads higher than the room stats as it's in the airing cupboard with the uvc. Would that affect anything if I was to set it up as you say?

In an ideal world, you would have the Samsung controller in a central position in the house where it can be easily kept and eye on, and where it can sense the room temperature.

If it were my system, I'd re-use the wires that run to one of your thermostats to reposition the Samsung controller downstairs, and run an extra 2 core cable from the PWM pump drive, to the primary pump.