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Author Topic: New ASHP Install  (Read 11008 times)
JonG
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« Reply #30 on: December 12, 2011, 09:55:25 PM »

Hi Mike, whereabouts are you, we are indeed installers and in the North West. The only reason I sound like I know what I am talking about is having made mistakes and learned from them the hard way!

In fairness there are quite a lot of issues which crop up due to ignorance and ill advice from manufacturers who don't really know how best to apply the technology.

Jon
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mpooley
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« Reply #31 on: December 13, 2011, 08:22:07 AM »

ah I'm in sunny Norfolk mate. what a shame.

one thing you may be able to comment on though is that all the installers I have had give me quotes said that i should not change any of my rads! just suck it and see! they reckon that most of their customers are happy and find out that the system works fine.

I'm afraid I don't believe it really- I want to - but i don't.
No one has offered to do a proper survey and calculate individual heat requirements for each room!

Fortunately I have! 
I have also tried to work out the heat output from normal rads at different water temps.
I am pretty unsure of this as I couldn't find much info on it but I made a little spreadsheet where I estimate the size needed for various temps.
At 35c it was  8 times the size of a rad at 75c water

I am assuming though that having the system on 24/7 will make a big difference to that but am not sure how to work it out.

thanks]

Mike
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It's not easy having a good time. Even smiling makes my face ache.

“Science is the belief in the ignorance of experts.” Richard Feynman
StationHouse
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« Reply #32 on: December 13, 2011, 08:49:52 AM »

I got installers with that 'suck it and see' attitude too...

'We will just connect the ASHP to the existing pipework and radiators'

1) It clearly stated that the EcoDan required 15mm for the high flow rates required, we had microbore!!!

and

2) the existing sluged up rads were undersized for LPG GCH never mind the low grade heat from an ASHP!!!

Installers with this attitude are chancers clearly not qualified in any way whatsoever and should be shown the door and told why...

Do you really think they will come back to rectify once they have your cash....?

I'd love to name names but probably not the done thing as one company quoted me £14k to install a Daikin Altherma connected to existing rads/pipework when the ASHP itself was about £6k. So thats £8k to install an ASHP!!!!!!!!!!!!!!!!

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bassman
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« Reply #33 on: December 13, 2011, 09:06:39 AM »

£14K was "day light robbery" - my Daikin 16kW monobloc was supplied and installed for £6300 and that included extra pipework to retain my existing oil boiler that I wanted to keep for "backup" purposes.

I supplied the concrete base and put a hole through the wall for the pipework etc.
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Daikin 16kW Monobloc ASHP - Stovax 8kW multifuel stove
StationHouse
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« Reply #34 on: December 13, 2011, 09:14:21 AM »

It's not just ASHPs, one of my solar quotes specified completely the wrong grade of wiring for the proposed panels so they don't even know the spec what they were installing  facepalm

No point in naming them as I doubt they'll still be in business following the FIT change  Smiley

Cheers
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titan
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« Reply #35 on: December 13, 2011, 09:15:40 AM »


one thing you may be able to comment on though is that all the installers I have had give me quotes said that i should not change any of my rads! just suck it and see! they reckon that most of their customers are happy and find out that the system works fine.


While not defending  misleading advice, they may have a point. Most so called heating engineers ( plumbers) usually grossly oversize carbon fuelled  systems including the rads and boiler ( unless they are working to a fixed price cheap quote) so you have nothing to lose trying your existing system which may have also been installed before other improvements like cavity wall insulation etc.
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mpooley
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« Reply #36 on: December 13, 2011, 09:38:40 AM »


one thing you may be able to comment on though is that all the installers I have had give me quotes said that i should not change any of my rads! just suck it and see! they reckon that most of their customers are happy and find out that the system works fine.


While not defending  misleading advice, they may have a point. Most so called heating engineers ( plumbers) usually grossly oversize carbon fuelled  systems including the rads and boiler ( unless they are working to a fixed price cheap quote) so you have nothing to lose trying your existing system which may have also been installed before other improvements like cavity wall insulation etc.

Yes I can see your point on that one but they probably at least make an effort lol

in my case the house is a renovated barn which was basically derelict so most walls are new and had a good standard of insulation by 1990 standards.
in fact the rads seem undersized for a normal high temperature system to me.
The pipe work is very poorly sized - some rads just would not get any flow until i re sized some of the pipes.


thanks

Mike
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It's not easy having a good time. Even smiling makes my face ache.

“Science is the belief in the ignorance of experts.” Richard Feynman
titan
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« Reply #37 on: December 13, 2011, 09:53:07 AM »

Jaga do some nice low temperature rads,  www.jaga.co.uk/products/catalogue/energy-savers        I was considering the mini trench rads for upstairs ( new build) but in the end didn't put any in as my calcs say the ground floor ufh is enough for the whole house, time will tell Smiley.
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StationHouse
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« Reply #38 on: December 13, 2011, 09:53:32 AM »


one thing you may be able to comment on though is that all the installers I have had give me quotes said that i should not change any of my rads! just suck it and see! they reckon that most of their customers are happy and find out that the system works fine.


While not defending  misleading advice, they may have a point. Most so called heating engineers ( plumbers) usually grossly oversize carbon fuelled  systems including the rads and boiler ( unless they are working to a fixed price cheap quote) so you have nothing to lose trying your existing system which may have also been installed before other improvements like cavity wall insulation etc.

Never seen an oversized GCH rad system, indeed rads in newer builds rads are so teeny that once when heating a brand new house from cold [bristol] I just could not get the house up to temp for a whole day... I even pushed the bed up against the rad! Strangely I find most new builds cold, some just go cold as soon as the GCH is off...

Proper heating engineers are just that... engineers. Each room needs to be calculated appropriately taking into account age of building, celing heights, glazing, insulation etc. Pipework and flow rate can also make or break a system especially with ASHP as all the pipework needs to be insulated too.

No wonder there are so many bad ASHP installs out there...
« Last Edit: December 13, 2011, 09:55:58 AM by StationHouse » Logged
mpooley
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« Reply #39 on: December 13, 2011, 09:59:40 AM »

mmh i never thought about pipe runs being insulated!

in the loft etc they are of course but not in the floor .

will that really make much difference though ?
wouldn't it be just like a little underfloor heater

I will try and run the boiler at 45c - 24/7 for a week maybe and see how it works.
That should test it i suppose?

Mike

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It's not easy having a good time. Even smiling makes my face ache.

“Science is the belief in the ignorance of experts.” Richard Feynman
StationHouse
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« Reply #40 on: December 13, 2011, 10:30:24 AM »

My flow temp over this winter so far is usually around 37c so over long pipe runs the insulation is essential being a suspended timber floor. Tis cold under there... There is the usual insulation between the joists which helps too.

Hope this helps

Cheers
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titan
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« Reply #41 on: December 13, 2011, 10:51:25 AM »


one thing you may be able to comment on though is that all the installers I have had give me quotes said that i should not change any of my rads! just suck it and see! they reckon that most of their customers are happy and find out that the system works fine.


While not defending  misleading advice, they may have a point. Most so called heating engineers ( plumbers) usually grossly oversize carbon fuelled  systems including the rads and boiler ( unless they are working to a fixed price cheap quote) so you have nothing to lose trying your existing system which may have also been installed before other improvements like cavity wall insulation etc.

Never seen an oversized GCH rad system, indeed rads in newer builds rads are so teeny

A developer build would be covered by the bold bit above
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JonG
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« Reply #42 on: December 13, 2011, 09:25:25 PM »

Just to put a slightly different perspective on things, the approach where existing rads are used stems directly from training that I undertook years ago with Mitsubishi and Ice Energy who's stock in trade approach was just that. If the installers have not moved on from this they will still approach projects from this perspective until Feb next year. Both companies took the view that cold spots could be tackled post installation and flow temps that were recommended were far too high for true efficiency. We are now very wary of the Japanese units, mainly because of the lack of hydraulic design and knowledge that is exhibited by the manufacturers.

It was and is to a degree also commonplace and accepted practice to oversize boilers though, simply because they were sized to be able to deliver a rapid ramp up of heat in a property from a standing start and percentage uplifts were often included on the heat loss to achieve this which then impacted radiator size too. Modern units will also ramp down significantly way below what an inverter driven HP will do, so gas usage is matched against load much better. Oil boilers are on off though and rely on the mini buffer of their jacket to reduce cycling.

Rarely though are the sizings sufficient to cope with the low flow temps required to run a HP efficiently. Mike if you want to work out your own rad sizings you need to heat loss each room, find out the rad manufacturers factor for the mean water temp that will be circulating against the design temp for the room, apply this to your heat loss and then choose a rad from their existing (Delta-T 50) schedule to meet your revised heat loss.

The mean water temp is dictated by the delta-t that your chosen HP needs, which may be between 5 and 10 degrees depending on the unit.

If you have a look on the Microregeneration Website under the installers section the new standards (MCS3005v3) confirm exactly how the heat loss will be calculated after Feb, what the design outside temp should be for your location to achieve 100% coverage and there are some look up tables for heat emitters because installers will have to give a star rating for efficiency based on the flow temp required to achieve design temp in the worst performing room with the emitter selected.

In terms of pipework insulation, this is very important, you can get away without it but why lose heat to a space that you do not need to heat, plastic has a lower level of heat loss so is a good choice under floors, it also requires less elbows so all important flow rate is improved.

I've said it before but seriously consider a buffer to preserve the flow rate, we just about hit nominal on Daikin's with 35mm into a buffer, so imagine how tricky it is through an entire system and rad valves. Throw in some sludge a few years on, and what might work day 1 won't be quite as good later on. As I said before though although a buffer is a good addition to any ASHP, you cannot integrate them properly with a Japanese unit, because they are looking for an on/off signal as opposed to a resistance based thermistor measurement, so you can't weather compensate the buffer. Daikin's will load compensate but compressor wear is still a concern because it samples from the base of the buffer where the return is coolest and does not allow the buffer to decay before being called back in.

Unfortunately the HP industry is hugely technical and errors are very easily made, often in complete ignorance. Just try and arm yourself with as much info as possible and pick your installer wisely. A good source of info is also the Refrigeration Engineers Forum which gets a bit techy but is a good place to lurk and learn. If you have an idea of which unit you are interested in I may be able to get an installer recommend from 1 of the reps we deal with locally.

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mpooley
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« Reply #43 on: December 13, 2011, 10:30:00 PM »

Thanks Jon
I have downloaded the PDF's and when i get a minute or hour or day or two will try to understand it Wink

It looks like it's going to be a difficult choice !

Mike
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It's not easy having a good time. Even smiling makes my face ache.

“Science is the belief in the ignorance of experts.” Richard Feynman
StationHouse
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« Reply #44 on: January 18, 2012, 05:22:43 PM »

£850 RHI payment finally been recieved  Smiley

And I thought registering for FITs was slow  Wink
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