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Author Topic: Whole system config help needed  (Read 6045 times)
wrigpm
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« Reply #15 on: November 08, 2009, 09:58:43 PM »

My tanks/system components are in my rear plant room - a specially designed area for these components with lots of space.  It is already well insulated and, like you, I use very thick insulation.  I agree with your philosophy but pipe insulation losses would be swamped by losses in a badly configured plumbing system - hence this is what I want to sort out first!!

PLEASE help with that!
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wyleu
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« Reply #16 on: November 08, 2009, 10:23:17 PM »

It really does depend on what you expect to get out of the system. Is the UFH installed, laid out, designed or just a pipe dream?  How large a area does it cover and have you designed it yourself or has it been designed by the pipe manufacturer? Are you filling bath's or driving showers and at what temperature do you hope to run these components. The system that mostly fills baths might be considerably diferent from that which provides good showers. Have you chosen at temperature at which you wish to drive the UFH? High temps mean it will react quickly but your GH system will be running less efficiently to reach that temperature. Do you wish your solar to contribute to the UFH or is it going to purely provide assistance to a boiler?
We are not trying to be evasive but you have to give some indication of load and the expected performance. This whole excercise is one of failing to deliver a resource gracefully, and as such those are all terms that you define around your system. That is why virtually every plumbing system is bespoke but most electrical systems follow very standard patterns. I would be surprised if someone were to draw you an overall diagram because it's so bespoke. This also applies to what gets joined to what, there's many many ways of doing it, and a few of them actually make sense.

Most peoples designs in such a situation tend to arise from thought experiments extrapolated from specification sheets from the equipment manufacturers, and this really what you will have to do.

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welshboy
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« Reply #17 on: November 11, 2009, 08:15:54 PM »

This is what I have if it is of any help.
WRB09 heat pump -> indirect 170l preheat tank-> underfloor heating.    No buffer Tank
The cold in feeds the preheat tank which feeds via a pump the dhw (again 170l) tank which supplies the hot water.
Plan to add solar thermosyphon ( using wookey principle- willis solar syphon type )to the dhw tank next spring.
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Brandon
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« Reply #18 on: November 12, 2009, 08:29:07 AM »

- a specially designed area for these components with lots of space. 

Yet it would seem that you are trying to cobble something together with a couple of old cylinders that are quite possibly not suitable.

I would start with the premise of a thermal store.
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changing the world, one roof at a time.

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wrigpm
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« Reply #19 on: November 12, 2009, 01:46:51 PM »

Brandon

Bit upset/offended by that!  Situation is not what you think:-

Original heatpump/cylinder/design done by a company that has now gone bust
Paid 1000's for heatpump/pipework/cylinders - all down the drain!
'thermal store' did turn up but turned out to be a standard cylinder

So, not trying to 'cobble something together' - just trying to avoid wasting 1000's again!  All the components are new as this is a new build

Hope that helps to clarify the real situation.
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wrigpm
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« Reply #20 on: November 20, 2009, 12:02:32 AM »

All

Have spent a long time looking through all the posts you have suggested and that I can find and have a proposed design that I would like comments on.  Principal of operation is:-

Summer
  • Solar panels heat DHW/RH cylinder then once that is hot heats the left hand tank
  • If no solar then left hand cylinder can heat DHW/RH cylinder or GSHP can be switched on
  • UFH driven from either stored/spare heat in LH cylinder or turn heatpump on


Winter
  • RH cylinder used as buffer tank
  • GSHP used to heat RH/DHW cylinder and/or UFH
  • Immersion top up of DHW/RH cylinder if required

Thoughts/modifications from people greatly appreciated.


* Entire plumbing system - new heatpump - basic diag.jpg (51.69 KB, 953x572 - viewed 373 times.)
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lightfoot
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« Reply #21 on: November 20, 2009, 08:16:23 AM »

To be fair to Brandon etc, I can see where he was coming from and I'm sure he didn't mean any offence.  As for making the best of what you've got - I think in principle, the way you have rearranged things in your latest sketch is OK and may help in some way to make the most of off-peak tariffs and reduce the heat pump start-up cycles etc etc.

For the record, the tank on the left would indeed be acting as a thermal store/accumulator/buffer - however, at the risk of sounding pedantic - the right hand tank is technically a indirect DHW storage cylinder and not a thermal store as labelled on you sketch.  Also, I assume you made a typo when describing the winter operation....'RH cylinder used as buffer tank'....and meant the LH tank?


Hope that helps,

LF.
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iann41
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« Reply #22 on: November 20, 2009, 08:25:50 AM »

What is the motorised valve for just after the G/S heat pump?

I also think the hot water pump should be on the cold side, maybe just before the G/S heat pump and reposition the motorised valve to the bottom of the heat store.

Ian
« Last Edit: November 20, 2009, 08:28:44 AM by iann41 » Logged
KLD
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« Reply #23 on: November 20, 2009, 09:08:23 AM »

Re. winter operation: the UFH will need say 40C flow, depending on heated floor area and heat load of the heated rooms. In order for the heat exchanger in the HW cylinder to transfer any heat at all, that cylinder need to be below those 40C. It looks like in winter the immersion will not be a backup but a regular top-up?

Klaus
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wrigpm
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« Reply #24 on: November 20, 2009, 10:43:30 AM »

Guys

Thanks for the info/help so far.  To answer the questions:-

  • Yes, you are right - std indirect mains pressure tank - label wrong
  • Typo - did mean LH
  • Motorised valve on heatpump output is to ensure that if GSHP is off and UFH etc is on that it draws the water through the cylinder and not the GSHP
  • Reposition of pump - yes probably right!
  • I run my UFH at 35degrees.  I leave the WRB09 as default i.e. in 'turn off at return temp of 42 degrees'.  I am assuming that the incoming water will be cold in winter (0-5 degrees) so think the GSHP will raise this to close to 42 and the immersion do the rest (although we have tried showers at 40 degree's and they are tolerable!)


Again, thoughts appreciated!
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lightfoot
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« Reply #25 on: November 20, 2009, 11:07:56 AM »

What is the motorised valve for just after the G/S heat pump?

I also think the hot water pump should be on the cold side, maybe just before the G/S heat pump and reposition the motorised valve to the bottom of the heat store.

Ian

I don't think that would work Ian? - and for this application I would keep the pump on the flow, also I had assumed the GSHP had it's own primary pump?

Alternatively - to pick up on what KDL is saying - if the GSHP has the ability modulate the flow temperature, to cater for DHW etc, and if you didn't wish to heat the whole thermal store too - you could connect up the thermal store in parallel, by moving the primary flow from the GSHP to the top connection of the thermal store, ie tee into the flow to the UFH & DHW circuit, with another zone valve between the tee and the thermal store.

One other thing I've just noticed - you may have just omitted to show it - but you will require a suitably sized EV on the primary side (connected to the cooler return to the store/GSHP, to minimise heat loss).

« Last Edit: November 20, 2009, 11:20:50 AM by lightfoot » Logged

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wrigpm
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« Reply #26 on: November 20, 2009, 11:27:16 AM »

Lightfoot

On my first diagram I did have the GSHP 'T'd into the top connection of the LH cylinder - can't rememeber why I moved it now!!  Ahh yes, remembered!  I thought that the circulator pump (which is very strong in the WRB09/GSHP!) might de-stratify the cylinder if it went into the top.

My understanding of the way the WRB09 works is that the output temp would be maintained by the heatpump to be, say, 10 degrees above the return temp.  Both IP & OP temps would rise (maintaining the difference) as the temp of the store etc rises until the return temp to the WRB09 hits the the cut off temp of the heatpump (42 in this case).

I have only shown the simple diagram and have left off the EV, pressure valves, filling loops etc.
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welshboy
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« Reply #27 on: November 22, 2009, 10:07:58 AM »

All

Have spent a long time looking through all the posts you have suggested and that I can find and have a proposed design that I would like comments on.  Principal of operation is:-

Summer
  • Solar panels heat DHW/RH cylinder then once that is hot heats the left hand tank
  • If no solar then left hand cylinder can heat DHW/RH cylinder or GSHP can be switched on
  • UFH driven from either stored/spare heat in LH cylinder or turn heatpump on



Winter
  • RH cylinder used as buffer tank
  • GSHP used to heat RH/DHW cylinder and/or UFH
  • Immersion top up of DHW/RH cylinder if required

Thoughts/modifications from people greatly appreciated.
Just an alternative- please excuse the childish drawing but hopefully you get the idea.
You want ufh with heatpump not cycling- adjusting parameter sp01 and the 2nd timer does that and therefore the store concept is redundant.
Solar could be to the biggest cylinder first then to the twin coil one as a dump.
the twin coil one is a preheat feed for the single coil dhw.

It is much simpler.


* option.JPG (61.29 KB, 1024x768 - viewed 310 times.)
« Last Edit: November 22, 2009, 10:10:30 AM by welshboy » Logged
welshboy
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« Reply #28 on: November 22, 2009, 05:33:24 PM »

Just another thought - unless you are generating your own electric the design you propose will cost you more.
To run the heatpump at 42c instead of 32c (all that is needed for ufh) requires an extra 40% on your electric bill for the same btus needed. You could raise one of your tanks from 32c to 42c with about 2.5kwh on an immersion heater - far less than wasting it by running the heatpump harder. The break even is only about two hours heating by heatpump. Any more than two hours running per day costs you more in your system I think.
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Brandon
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« Reply #29 on: December 04, 2009, 11:14:29 PM »

what are the coils in these tanks/cylinders/stores?

Are they all of a sufficient area to be used for the solar coil? if not then I would argue that the choices ought to be made along the lines of what the coils will allow.

A 3port diverter will do the job of the 2 2ports on the solar return.

3port compensating for the underfloor?
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changing the world, one roof at a time.

Quality is never an accident; It is always the result of
high intention, sincere effort, intelligent direction, and
skilful execution; It represents the wise choice of many
alternatives.
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