Plate loading or coil UVC for heat pump

[JohnMo]

Seen a couple of plate loading UVC's on offer for heat pumps, as opposed to a coil. So PHE and small pump taking cold water from bottom and deposits at top of cylinder after heating.

 

One from Warmflow and the other from Mixergy. 

 

Advantages disadvantages?

[JohnMo]

Spoke with Warmflow their heat pump cylinder will only work with their heat pump, as the pump speed is controlled by the ASHP. Mixergy cylinder requires internet to function in the most part, so both are none starters for me.

 

Have decided to go slimline (easy access through loft hatch) 210L UV cylinder with 3m2 coil.

[JamesPa]

On 10/08/2023 at 15:29, JohnMo said:

Spoke with Warmflow their heat pump cylinder will only work with their heat pump, as the pump speed is controlled by the ASHP. Mixergy cylinder requires internet to function in the most part, so both are none starters for me.

Bit silly of Warmflow - they might have had a ready market!  Mitsubishi also do a plate loaded cylinder I think, not sure if it suffers from the same stupidity.

[JohnMo]

 

21 minutes ago, JamesPa said:

Bit silly of Warmflow - they might have had a ready market!  Mitsubishi also do a plate loaded cylinder I think, not sure if it suffers from the same stupidity.

Not sure any of think that far ahead.

 

Possibly only need a simple dT controller on a variable speed pump, to manage temperature rise across the PHE on the cylinder side. Or even simpler for a DIY solution - a gate valve to set flow rate on the cylinder side, and make the pump manual, then during commissioning set pump at best speed and use the gate to move the duty point on the pump curve to get the dT you want.

[JamesPa]

2 minutes ago, JohnMo said:

Possibly only need a simple dT controller on a variable speed pump, to manage temperature rise across the PHE on the cylinder side. Or even simpler for a DIY solution - a gate valve to set flow rate on the cylinder side, and make the pump manual, then during commissioning set pump at best speed and use the gate to move the duty point on the pump curve to get the dT you want.

The guy who is doing my ashp is fitting a PHE and pump to a off the shelf UVC.  It's more or less his standard install, although he has also retrofitted same to an existing VC.  When he does it I will find out what control he uses, probably your simple (second) suggestion above.

[joth]

1 hour ago, JamesPa said:

Bit silly of Warmflow - they might have had a ready market!  Mitsubishi also do a plate loaded cylinder I think, not sure if it suffers from the same stupidity.

I'm working next to one of this mitsu cylinders today. I'll take a look at see if it's speed controlled, but 99% sure it isn't as the FTC6 does not have any connection for variable speed output.

 

(It's also a kinda mad system design as it's being used for DHW only (passivehaus, no space heating) yet had a preplumbed cylinder with a couple redundant pumps and diverter valve in circuit. And then the primary side is so tiny (in part because of the PHE) that they've had to add a 50L buffer (volumizer) in series just to meet the manufacturer minimum system volume.  Seems a lot of faff for a DHW only system.)

 

[JamesPa]

55 minutes ago, joth said:

I'm working next to one of this mitsu cylinders today. I'll take a look at see if it's speed controlled, but 99% sure it isn't as the FTC6 does not have any connection for variable speed output.

 

(It's also a kinda mad system design as it's being used for DHW only (passivehaus, no space heating) yet had a preplumbed cylinder with a couple redundant pumps and diverter valve in circuit. And then the primary side is so tiny (in part because of the PHE) that they've had to add a 50L buffer (volumizer) in series just to meet the manufacturer minimum system volume.  Seems a lot of faff for a DHW only system.)

 

All that piping just for dhw?  As you say it seems kinda mad, surely a tank with integrated hp is better for this situation.

[Iceverge]

1 hour ago, joth said:

I'm working next to one of this mitsu cylinders today. I'll take a look at see if it's speed controlled, but 99% sure it isn't as the FTC6 does not have any connection for variable speed output.

 

(It's also a kinda mad system design as it's being used for DHW only (passivehaus, no space heating) yet had a preplumbed cylinder with a couple redundant pumps and diverter valve in circuit. And then the primary side is so tiny (in part because of the PHE) that they've had to add a 50L buffer (volumizer) in series just to meet the manufacturer minimum system volume.  Seems a lot of faff for a DHW only system.)

 

 

They'll have plenty of space heating I fear with all the heat leakage through those tank connections no matter how good an insulating job is done on the pipes. 

[JamesPa]

3 hours ago, Iceverge said:

 

They'll have plenty of space heating I fear with all the heat leakage through those tank connections no matter how good an insulating job is done on the pipes. 

It looks worse than the inside of my airing cupboard which yesterday I was easily convinced should be stripped out in its entirety.  The airing cupboard is the result of successive mods, not a one off design.

[joth]

8 hours ago, joth said:

I'll take a look at see if it's speed controlled, but 99% sure it isn't as the FTC6 does not have any connection for variable speed output

I stand corrected, the FTC6 does indeed have a output for controlling primary pump speed, and it is hooked up on the preplumbed cylinder. Marked CNPWM / WH on the motherboard.

The MIs have it on the drawings but don't mention its purpose in the text at all, which is why I've never noticed it or tried to hook it up in my own install.

 

 

 

Edited August 17, 2023 by joth

[joth]

3 hours ago, JamesPa said:

It looks worse than the inside of my airing cupboard which yesterday I was easily convinced should be stripped out in its entirety.  The airing cupboard is the result of successive mods, not a one off design.

Yeah other than the buffer tank (and a lot of unrelated loose WIP wiring) this is all the preplumbed cylinder you're looking at here. It is a messy job even if you do want the 2 zones of space heating, but for a DHW only system it is crazy.

 

[Iceverge]

Would it not be more sensible to just install a plain DHW HP UVC and sell this complicated mess?