ASHP to buffer only :o/

[Mr Blobby]

In a brief conversation with our plumber last week he said our ASHP flow and return will go to the buffer tank only.  And then from the buffer to the hot water cyclinder and ufh manifold (with a valve switching betwen the two circuits of course)

That's odd I thought.  I must have misheard him.  I explained to said plumber about how the UFH flow temp will be way below the DHW flow temps so that's not really going to work because I really dont want to maintain a 50 degree buffer, but he was quite insistent.

 

Surely ASHP must be connected to both buffer and UVC with a 3-way (or 2x2-way) valve switching flow between the two.   I'm pretty sure that's how the ASHP controller expects to be set up.

 

Is my plumber talking nonsense?  Or have I missed something here?

 

 

Edited July 4 by Mr Blobby

[IanR]

15 minutes ago, Mr Blobby said:

Is my plumber talking nonsense? 

 

Yep. Is it his first install?

 

3-Way before the buffer to select between buffer and UVC.

Edited July 4 by IanR

[JohnMo]

Talking out of their butt. Biggest question for me would be, why do I need a buffer at all? One zone or a couple of large zones, zero need. I suspect they will cover your house in thermostats, all third party on off ones, screw up your efficiency and charge you a pretty penny also.

 

If they are not budging on buffer, ask how he is balancing the flow either side of the buffer, if asks why, look to sack him, as they really has no clue what he's doing and why.

 

KISS the heat pumps best friend 

[IanR]

12 minutes ago, JohnMo said:

ask how he is balancing the flow either side of the buffer,

 

I'm firmly on the "ASHP flow rate does not have to (and will not) equal heat emiiter flow rate" side of the buffer (3P & 4P) argument. Mine is designed not to and works perfectly well, meeting manufacturer declared COP.

 

But, if you can avoid a buffer, save the capital investment.

Edited July 4 by IanR

[JohnMo]

2 minutes ago, IanR said:

 

I'm firmly on the "ASHP flow rate does not (and will not) have to equal heat emiiter flow rate" side of the buffer (3P & 4P) argument. Mine is designed not to and works perfectly well, meeting manufacturer declared COP.

 

But, if you can avoid a buffer, save the capital investment.

I may be wrong here, but don't you have a fairly large well designed buffer (Nibe) or am I thinking of someone else?

Most are not designed well to promote a thermocline, and small ones could not maintain it anyway. So mixing occurs to increase heat pump flow compared to delivery.

 

The way the OP installer is proposing to install the buffer is rubbish and would not comply with any manufacturers design scheme. DHW always should be before buffer, the cylinder does not need a buffer.

[IanR]

2 minutes ago, JohnMo said:

I may be wrong here, but don't you have a fairly large well designed buffer (Nibe) or am I thinking of someone else?

 

I do. 

 

2 minutes ago, JohnMo said:

Most are not designed well to promote a thermocline, and small ones could not maintain it anyway. So mixing occurs to increase heat pump flow compared to delivery.

 

If it's a (ASHP) manufacturer approved install I'd expect it to work as designed. You'd need to assess case by case to say a particular install is not working as designed. 

 

6 minutes ago, JohnMo said:

DHW always should be before buffer, the cylinder does not need a buffer.

 

Agreed, as per my comment before yours.