Posted by: @jamespa

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Viessman pre-heat a specific defrost

Grant have much to same and can even be placed outside, next to the HP.

Yes when defrosting the heat has to come from some where and by changing to the 3 port buffer it will still come from the house loop and need to be replace. So it will still work the same as your open loop.

Its the anti-freeze cycle that just keeps water flowing through the heat pump for 12hrs when it's below 4c, that will draw heat from the house with no buffer. And as the CH pumps are off at this time it confines the water flow to just the buffer. 

When the HP starts up and flow temp goes up it will not worry about what's in the 3 port buffer and if the flow is still greater from the HP, it will heat up the buffer and help reduce the defrost

Posted by: @heacol

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I don't believe the installation of a buffer tank, complies with the building regulations.

 

 

Nice one!

Posted by: @jamespa

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Just thinking about this measuring the temperatures on all 4 ports

That's how we start, 4 temps on the 4 ports. It showed we had a imbalance of 5° across the top, which I wanted to reduce having looked at the various videos on the subject.

And YES it is hard adjusting everything, leaving it 24 hrs and rechecking. If I had installed flow meters both side it might have been quick.

Learnt a great deal about my system doing this and quite happy to spend £200 this summer to put 4 valves, 2 flow meters and bypass pipes in, so once again I can check various combinations to see which works for us.

PS I've also learned/worked out that it could be automated just on temp and having automatic adjusted flow meters, but that's starting to get beyond me so no longer looking at it

Posted by: @heacol

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I don't believe the installation of a buffer tank, complies with the building regulations.

Wow! 😮 

I think this needs raising with Citizens' Advice.
They hold the remit for operating the Consumer Rights Act (2015).

I suspect they have a heat-pump specialist to advise the separate offices.
They must have centralised policies on which cases can go to arbitration.
I already know they have a representative who specialises in Smart Meters, for example.

@editor - the ball's just bounced into your side of court

Posted by: @uk_pete_2000

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Its the anti-freeze cycle that just keeps water flowing through the heat pump for 12hrs when it's below 4c, that will draw heat from the house with no buffer. And as the CH pumps are off at this time it confines the water flow to just the buffer. 

OK thats definitely a different problem.

The buffer will presumably cool down fairly quickly in relation to 12 hrs and at that point I imagine that the heat pump might switch itself on to heat, in order to protect itself.  This being the case would it be any worse simply having a pressure operated bypass valve?

That said, when its 4C outside could you reasonably operate 24*7, or is your heat pump so oversized that this isnt possible/cost effective.  

Posted by: @transparent

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Posted by: @heacol

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I don't believe the installation of a buffer tank, complies with the building regulations.

Wow! 😮 

I think this needs raising with Citizens' Advice.
They hold the remit for operating the Consumer Rights Act (2015).

I suspect they have a heat-pump specialist to advise the separate offices.
They must have centralised policies on which cases can go to arbitration.
I already know they have a representative who specialises in Smart Meters, for example.

@editor - the ball's just bounced into your side of court

Well this is an interesting line of thought and I wonder where MCS would sit (on the fence? as far away as possible?)

If manufacturer insists on a buffer tank I cant see a case based on building regs succeeding (the word 'reasonable' applies), but if they don't (or strictly didn't at the time of installation ) then there is a good argument.  In that situation the case would be against the installer.

The heat pump only turns on when we request heat. Never really tested what happens if we leave if off for 24hrs and its below 4°. I think even our house would have lost so much heat that it would take 24hrs to get back up.

Posted by: @jamespa

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That said, when its 4C outside could you reasonably operate 24*7,

It's not that it can not work 24hrs, I did it for a couple of days at the start of Jan and it worked fine. 

The problems are, we need minus figures to keep it working 24/7

It's the fact it will not go below 23° flow temp and still heat the house up when it's freezing outside. 

At preset I just leave it at 27° flow temp. Then on a average day I run it 6hrs, much colder nights I run it for 8hrs a day and if we get very cold days/nights I'll run it 12hrs a day.

And YES it's oversize due to MCS calculations at the time. But it will cost too much to replace it, so I work with it.

Posted by: @uk_pete_2000

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The heat pump only turns on when we request heat. Never really tested what happens if we leave if off for 24hrs and its below 4°. I think even our house would have lost so much heat that it would take 24hrs to get back up.

Posted by: @jamespa

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That said, when its 4C outside could you reasonably operate 24*7,

It's not that it can not work 24hrs, I did it for a couple of days at the start of Jan and it worked fine. 

The problems are, we need minus figures to keep it working 24/7

It's the fact it will not go below 23° flow temp and still heat the house up when it's freezing outside. 

At preset I just leave it at 27° flow temp. Then on a average day I run it 6hrs, much colder nights I run it for 8hrs a day and if we get very cold days/nights I'll run it 12hrs a day.

And YES it's oversize due to MCS calculations at the time. But it will cost too much to replace it, so I work with it.

All fair enough.  I dont think I can really add much more beyond what I've already said.  if somehow you need to accommodate it switching itself on at 4C, but not heating, then a byass or buffer is the only way.  I would be concerned that, at - temperatures, the water would still cool below freezing if left off for 12 hours but recirculating through the unit (unless the HP also switches to heat, which I imagine it might), I guess that where anitfreeze valves or glycol come in.

@iraknic, as promised, the episode is out. Well worth watching IMO. Your case is around the 23 minute mark.

@editor thanks, i will watch it

 In the coming weeks, I’ll be scheduling another session on buffer tanks, where viewers can submit videos and images for our panel to assess and provide advice.

If you’d like to take part, please send us a question about your system and submit high-resolution photos and videos via WeTransfer.com to editor@renewableheatinghub.co.uk.

@iraknic out of curiosity how did you check your delta T. Was it just purely from your control panel?