making use of redundant solar coil

[toucan]

Hello,


I installed a newark solarcyl 140lt thermalstore cylinder about 3 years ago(solar and immersion only). For various reasons it was never connected to solar panels, being heated with immersion instead. The house(log cabin) is about to be incorporated into a mini district heating system provided by 22.5 kw pellet boiler. Can i keep this cylinder and use the solar coil to connect to the heating main.




Thanks
Toucan

 

[SimonG]

Is it unvented?

 

[Killy Bing]

I cant see why not
ring manufacturers about it.

assuming you're having having a Hiu (heat interface unit)
these come in various versions and some come as a "combi" set up meaning you wouldent need the stored water at all but you'd have reduced hot water performance.

if it comes as a system set up the. You need to have the coil zoned separately to the central heating system.

 

[toucan]

Hi simon G, no it's a vented combination cyl.

 

[SimonG]

Hi simon G, no it's a vented combination cyl.

I was just too lazy to look it up

KB's advice is the way to go then.

 

[Killy Bing]

I was just too lazy to look it up

KB's advice is the way to go then.

Unvented would be fine on district heating system run by a pellet if you're using a HIU anyway
no uncontrolled heat source on the system side.
think of the HIU as a heat exchanger

although to run a district heating system off a 22 kw pellet boiler you'd need a whacking big thermal store to make it effective surely so that you'd class as a buffer.

unless im barking up the wrong tree in the wrong forest....

 

[toucan]

Newark say it is ok. The system is already in place, Mcz musa 22.5kw pellet boiler coupled to 250lt unvented cyl, uponor heat main to two log cabins, I've been asked to install dhw cylinders and radiators in the cabins the second cylinder likely to be unvented. I'm not familiar with HIU's but the cabins will have their own controls and flow bypass.

 

[Jimbob]

22kw is tiny for district heat.

You could use the coil but it depends on it's area. We always try fit cylinders with the biggest coils possible to give greater return temp difference and not mess with the stratification of the buffer.

Not a fan of HIUs for dhw - they require a constant flow from the district heat so you don't have to wait for hot water, the down side to this is greater heat lose and destratification of the buffer.

 

[Killy Bing]

Newark say it is ok. The system is already in place, Mcz musa 22.5kw pellet boiler coupled to 250lt unvented cyl, uponor heat main to two log cabins, I've been asked to install dhw cylinders and radiators in the cabins the second cylinder likely to be unvented. I'm not familiar with HIU's but the cabins will have their own controls and flow bypass.

Google heat interface units.

basicly a boiler but its heat source is via a heat exchanger from the district heating

 

[Ermintrude]

Are the cabins second homes or are they commercial let's?

 

[Killy Bing]

...who did the calcs for the district heating, boiler and buffer sizing?

sounds like you might get blamed for a poorly designed system....

 

[Worcester]

The system is already in place, Mcz musa 22.5kw pellet boiler coupled to 250lt unvented cyl...

The start of someones problems .... There again I can be cynic sometimes. Someone trying to save a ha'porth of tar...

don't spoil the ship for a ha'p'orth of tar
• proverb Don’t risk the failure of a large project by trying to economize on trivial things. [referring to the use of tar to keep flies off sores on sheep (from dialect pronunciation of sheep as ship)]

 

[toucan]

'Are the cabins second homes or are they commercial let's'

all residential. 2 x 1 bed with shower. 1 x 2 bed & 2 wet room(unit with boiler/250ltcyl). I accept comments on questionable design. I'm not experienced in heating design myself, I'm lucky that I may be able to learn through this process, as will the designer! We've all got to learn somewhere and your not going to get this in the class room.

 

[Ermintrude]

Ok. Are the dwellings on heat meters? With a plate or is it all one big primary with zone valves?

 

[toucan]

Ok. Are the dwellings on heat meters? With a plate or is it all one big primary with zone valves?

primary heat main. uponor 25mm I think

 

[toucan]

with zone valves

 

[Ermintrude]

Possibly use it on zone valves. System sounds a bit stretched tho. Why not use it as solar and get more £££££ but you will need mcs installer.
If you did use cylinder set it to heat up at 4am so it's not jobbing all the heat from buffer!

 

[Worcester]

You keep mentioning the 250Ltr cylinder - is this a buffer tank or is it the DHW cylinder for the property where the boiler is / will be?

If the DHW cylinder - is there a buffer tank?

If the buffer tank, what arrangements for a DHW cylinder?

25mm main will be around 20.5mm id, sounds a bit small to me... anyone done a hydraulics and head loss design on this?

 

[Ermintrude]

Headless chicken

 

[Killy Bing]

Headless chicken

Ya think.

how far apart are the cabins to each other and to the plant room?
what pumps are you fitting?
whats your standing losses on the heatmain?

if 250ltrs is your store size then i'll put money on that being your first whopping issue

 

[toucan]

First cyl about 6-7 metres second 17-18m from boiler. Not sure what pump, it's in the pellet boiler unit. I have since found out that this system was in fact designed by company who installed unvented cyl and pellet boiler (solar thermal also). They are waiting for us to complete the plumbing of additional cylinders /central heating in log cabins before commissioning. I'll try to feed back on how it all goes. Thanks for all your comments.

 

[Worcester]

First cyl about 6-7 metres second 17-18m from boiler. Not sure what pump, it's in the pellet boiler unit. I have since found out that this system was in fact designed by company who installed unvented cyl and pellet boiler (solar thermal also). They are waiting for us to complete the plumbing of additional cylinders /central heating in log cabins before commissioning. I'll try to feed back on how it all goes. Thanks for all your comments.

So it sounds like no buffer tank. At least it isn't going to be your problem when this system doesn't perform well, and uses far more fuel (pellets) that it should do! Without a buffer the boiler will be cycling far too frequently, also sounds as is the inbuilt pump will struggle with effectively 6 zones (3 x Heating, 3 x DHW).

 

[toucan]

Thanks for your comments & opinions. I'll try to keep you posted re - performance. Incidentally Heat meters will be installed.

 

[Worcester]

If you are installing heat meters, make sure you install them in compliance with this guide, else they don't work properly!!

About 75%on current heat meter installations are wrong and not recording the proper results.


http://www.microgenerationcertifica...ering Guidance Issue 1.0 2013.12.16 FINAL.pdf

it came from this and was turned into an ID ten T's guide
https://www.ofgem.gov.uk/ofgem-publications/83032/rhiguidance-meteringplacementexamples.pdf

and here is the one from DECC for the Domestic RHI:
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/211993/A_guide_to_metering_for_payment_for_the_domest_Renewable_Heat_Incentive_.pdf


and here's one from DECC on how NOT to install meters:
http://blog.decc.gov.uk/2014/02/18/installing-a-heat-meter-in-the-domestic-rhi-say-aaahhh/