house renovation

[Uncle Fester]

water is pumped around the panel from the drain back unit which transfers that heat to the unvented hot water cylinder, when the system is off, it makes no odds how efficient the panel may or may not be, as the system is off.
I'm not sure if they have any installed in Scotland, but I'm sure they'd tell you if you asked them.

The panels are made of aluminium sheet with 10 mm copper tube lazer welded to the collector panel.

 

[Dieselman]

I am beginning to feel like the straight man in our relationship.


would you like to expand on this?

0.020 W/m.K (≥ 45 mm)

Sorry, am I treading on your toes?

For those that don't know, the stone absorbs the heat from the house and normally leaches it off into the air at an alarming rate, adding exterior insulation traps the heat in so it can only radiate back into the house, which maintains an even temperature.
The more mass is heated the more even the temperature will remain.

Back to you finisterre.

 

[Dieselman]

when the system is off, it makes no odds how efficient the panel may or may not be, as the system is off.

Yes it does as the system will always cycle on and off as the store temperature rises or cloud blocks the sun. At that point the panel will lose the heat stored within it, but it will also be radiating heat all the time as it only has air as an insulant.
The greater the differential between the plate and the ambient, the greater the heat loss will be, on an exponential basis.

Ye canna beat the laws of physics captain.

 

[Ade B]

All good advice here (as ususal)

We've always been advised air source heat pumps are more cost effective than ground source as they don't need expensive boreholes or miles of pipework... the below surface pipe is obviously tricky in a small London plot so may make more sense with lots of space..

It may be worth taking some professional advice as not all properties are the same, orientation, prevailing winds etc. etc. all have an impact and a few hundred quid on an independent M&E consultant could save money in the long run - we recommend their appointment on most domestic projects as if nothing else they make getting through the rather tedious and long winded Doc L more straight forward, particularly where there is lots of glazing involved..

You need to be careful with insulating old properties - they are usually designed with lots of air movement in mind - make sure you allow sufficient ventilation to timbers if you are lining internally to prevent trapped condensation turning into rot.

Another thing to bear in mind is planning consent - worth a check with the local planners to make sure you don't fall foul of any conservation guidelines etc. they can be pernickety about all sorts of obscure things.

Don't install an Aga if you are looking for energy efficiency

Good luck and keep us posted.

Ade

 

[Uncle Fester]

Yes it does as the system will always cycle on and off as the store temperature rises or cloud blocks the sun. At that point the panel will lose the heat stored within it, but it will also be radiating heat all the time as it only has air as an insulant.
The greater the differential between the plate and the ambient, the greater the heat loss will be, on an exponential basis.

Ye canna beat the laws of physics captain.

That maybe true, but all I can tell you is the system works and gives you hot water on most days of the year, even if it's only 35 deg C, and it's more or less free (notwithstanding installation costs etc)
Scotland may be a different kettle of fish climate wise, and only a local installer would be able to tell you how effective any solar system would be.

I think a mix and match system with several types of fuel and renewables would be the ultimate answer, but at what initial cost?

 

[finisterre]

I had a job fitting kingspan for a JCB engineer. He was so **** about the heat loss through the bottom of internal walls that he wanted me to line them too. Being a rubbish employee I did all the other stuff first then sort of lost interest. I believe the benefits of thermal inertia outweighed the loss through the internal wall foundations. He thought the well insulated stone flooring would do the job. He said his calculations were unquestionably correct. He may have been right.


DM - I don't have territorial issues.

 

[Dieselman]

Scotland may be a different kettle of fish climate wise, and only a local installer would be able to tell you how effective any solar system would be.

It will definitely work but will require a higher panel to storage ratio.
As a year round average, SE England gets approx 1300W/SqM per hour of solar radiation, Scotland will see about 1000W/Sqm/hour so requires greater collector area.

 

[Ade B]

Kingspan have a useful website and very helpful technical support - if you ring them up they do U value calcs for you and produce documentation tailored to your proposed wall/floor/roof build ups to appease lazy building control officers.

We specify it all the time - and contractors install Cellotex

 

[Uncle Fester]

It will definitely work but will require a higher panel to storage ratio.
As a year round average, SE England gets approx 1300W/SqM per hour of solar radiation, Scotland will see about 1000W/Sqm/hour so requires greater collector area.

Then maybe the 150 litre with 3 or four panels of 2.5 m2 (each) would work better.
The 90 litre store has one panel, the 150 can be 2,3 or 4 panels.

 

[Dieselman]

Then maybe the 150 litre with 3 or four panels of 2.5 m2 (each) would work better.
The 90 litre store has one panel, the 150 can be 2,3 or 4 panels.

That's a lot of panel area per litre of stored water. How many panels do you have, 2 * 2.5m each?
I was bothered about Summer overheat, but now remember you said it was a drainback system, which makes a difference to the lost heat when off.
There are pro's and con's to each system type.

 

[Uncle Fester]

the system is not perfect by any means, but has it's merits, and is worth looking into I think, mainly due to the fact that you get to use the "free" hot water every day, regardless of temperature, as it is fed into a combi boiler which will "top up" the water temp to around 60 deg C, and if the stored water temp is above 60 deg C then the combi is bypassed and not gas is burned.
Once the max water temp of around 75 deg C is reached in the storage tank, then the drain back system shuts down, until the stored water temp drops, so overheat is not an issue, although the use of a blending valve is recommended before the water get to the taps/showers etc

 

[Dieselman]

Once the max water temp of around 75 deg C is reached in the storage tank, then the drain back system shuts down, until the stored water temp drops, so overheat is not an issue, although the use of a blending valve is recommended before the water get to the taps/showers etc

Mandatory if the store can attain over 55c.
My store maximum is set to 85c with panel re-cooling set to 140c. This has on occasion pushed the 200 litre store upto 90c, which is pretty warm.

 

[finisterre]

it is fed into a combi boiler which will "top up" the water temp to around 60 deg C

A few years ago when I was trying to sort our heating out I failed to find any boiler manufacturers that would guarantee the pipework and valves on the cold supply side to temperatures outside the normal ambient range. I don't know if that is still the case, but I found it to be an issue.