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webcmg
(@webcmg)
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@robl thanks for the reply. Your assessment of A, B, C is spot on. The garage isn't completely uninsulated but the loft space insulation can definitely be improved. We're working with the developer to identify and implement modifications to the house (snagging) and heating system (due to the poor performance in relation to comfort and efficiency) so don't just want to get it sorted myself and interfere with the process. For example, we know that we have some drafty windows and I have identified some other issues with the insulation in the main house.

Once that's been completed, I will be looking to make whatever improvements necessary to further improve efficiency because I'm concerned we have such a high kwh usage for heating in the winter. If unit prices go up after our fixed rate tariff we could be spending £750 per month in the winter to heat the house.

We have a very large south-facing roof, so would consider PV and batteries etc. However, I'm new to all this though so need to do some research to assess how this would work and how much it would cost.

The pipes under A do get very hot, could they be insulated, I assume not because they are controls? 


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robl
 robl
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@webcmg 

I think it is fine to insulate controls, just you can't get to them so easily.  It's electrical stuff that shouldn't be, as it is a heat source in it's own right and may overheat (electric valves, the head of an immersion).  Assuming that it all gets hot and is in a garage, I would insulate all of the stuff under A and the flexi pipe etc (assuming it gets hot) near it. 

You could put IWI on the wall behind, and build up a box out of some sort of foam insulation , XPS is the easiest to use I find, doesn't mind water, good to 90C or so.  Make the front of this box be removeable, so the controls can be got at if need be - I expect this is for swapping out the heat exchanger, or perhaps during a service. 

Alternatively you can add more pipe insulation to what's there, covering everything you can.  You can get neoprene flexible insulation to cover the flexi pipe too, and even insulation "jackets" for (manual) valves too.  You could bubble wrap around those and other manual valves, in a way that's easily removeable.

The pipe insulation that is there looks good, there are just lots of uninsulated bits, and there is a lot of pipework in a garage!  Pipe insulation isn't magic, it's only thin with a big temp drop across it.

Re-reading what you actually said though (!) it sounds like you want to assess rather than do.  Many organisations offer free loan of a thermal camera these days (Camb Carbon footprint, where I am, I am sure there are many others).  Or the (unused) dhw losses/day test I suggested.  Whatever the loss is, it will increase in winter as it gets colder.

PV is a great thing these days of high energy costs!  My advice is try and get as much as possible - 16A export is always allowed(often described as 4kWp), your dno may allow more.  PV+battery costs 2x, but it allows more PV, and allows better utilisation by you of the PV.  From scratch, I would go PV(max you can fit)+batt.  If that was too expensive, PV(max fit/afford)+hybrid inverter(limit to 16A out if dno insists) - then when funds permit get a batt.


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webcmg
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@robl cheers, are you suggesting removing and putting IWI behind the heat exchanger box? Or just around it?

Out of interest, where would source insulation and PV from?

Cheers


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robl
 robl
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@webcmg 

I expect the heatexchanger box will already be insulated inside.  If it's easy to open, take a look and pics are always good!  I'm suggesting insulation around the pipes and manual valve below it. 

It's only a little bit of insulation - you can get small amounts of XPS from ebay.  The pipe type insulation and bubble wrap can be found in diy stores. 

Lots of small companies install PV - ours was done by Navitron about 10 years ago.  They don't exist anymore sadly, probably as a result of the boom-bust of the PV industry as incentives change over time.  Ours has been great, it's made more elec than we have used in the last 10 years, and paid for itself now too.  Most PV elec is in the summer, (20kWh/day), while in winter it might b 2kW/day, so not a lot of use for directly offsetting a heatpump.  I'd suggest googling for them in your area.  Only choose "RECC" approved installers, which I think stops "double glazing" sales tactics etc.


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webcmg
(@webcmg)
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Posted by: @robl

@webcmg 

I expect the heatexchanger box will already be insulated inside.  If it's easy to open, take a look and pics are always good!  I'm suggesting insulation around the pipes and manual valve below it. 

It's only a little bit of insulation - you can get small amounts of XPS from ebay.  The pipe type insulation and bubble wrap can be found in diy stores. 

Lots of small companies install PV - ours was done by Navitron about 10 years ago.  They don't exist anymore sadly, probably as a result of the boom-bust of the PV industry as incentives change over time.  Ours has been great, it's made more elec than we have used in the last 10 years, and paid for itself now too.  Most PV elec is in the summer, (20kWh/day), while in winter it might b 2kW/day, so not a lot of use for directly offsetting a heatpump.  I'd suggest googling for them in your area.  Only choose "RECC" approved installers, which I think stops "double glazing" sales tactics etc.

Thanks, I was thinking of IWI on the entire room. The water to 46 deg and averages about 4kwh over the last few days. What are you doing with the excess electricity? 


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robl
 robl
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@webcmg 

Excess elec is a financial issue, rather than a green one; it will always find a good home, you just might not get paid for it! 

At the moment we are on a special trial tariff because we have a V2G Nissan Leaf, and we get paid to export electricity (the car charges at night, and then discharges to grid in the evening).  After the trial is over there's no incentive to export power, we will likely convert the car charger to V2H so excess solar would go to it and stop the car flattening(80%->20%) every evening into the grid!  Maybe we'll get a house battery too - that would allow us to have more PV - we cannot at present, as we are not allowed to export >16A due to limitations of the local grid.  Many people use an iboost or Solic 200 or similar solar diverter, to push spare elec to heating a water tank.  

We use ~6MWh/year in total (3MWh for "stuff", 1.5MWh for heating & dhw, 1.5MWh for driving the car.  Solar provides 3.5MWh/year.  Due to the V2G trial there's also the energy cycling of the car of ~4MWh/year in, ~3MWh/year out.  I'd love more PV, to break even over the year 🙂


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webcmg
(@webcmg)
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@colin hi Colin, any chance you can share your anti legionnela settings? System used 8kwh on this cycle last night and temperature is only reading 48 deg C. Thanks. 


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Colin
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Posted by: @webcmg

@colin hi Colin, any chance you can share your anti legionnela settings? System used 8kwh on this cycle last night and temperature is only reading 48 deg C. Thanks. 

Hi, no problem. I've attached the monthly DHW electricity consumption and yield as well to help you compare.

image
IMG 6962
IMG 6964

 


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webcmg
(@webcmg)
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@colin thank you, does your cylinder definitely hit the required temperature? 


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Colin
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@webcmg Yes, then it loses 0.5º C every few hours. The graph shows Thur (Anti-Legionella Day),  Friday and Sat night. 

image

 


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webcmg
(@webcmg)
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@colin my cylinder boost offset was 25k, so you know what this actually means? 


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webcmg
(@webcmg)
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20220529 210620
20220529 210813

A couple of pictures, the first is the inside of the heat exchanger box. The polystyrene seems to insulate well and is a tight fit. 

 

The second is a pipe "loop" for hot water that feeds back into the CW inlet. I understand that this is so hot water 'arrives' quickly at all outlets in the house. We have never plugged in or switched it on because hot water tends to be there very quickly anyway. However, I noticed the other day that this pipe was very warm to touch which surprised me and could therefore be inefficient if hot water circulates through it? I don't really understand what it does or how it works. Any thoughts on this welcome...


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webcmg
(@webcmg)
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Joined: 6 months ago
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Posted by: @colin

@webcmg Yes, then it loses 0.5º C every few hours. The graph shows Thur (Anti-Legionella Day),  Friday and Sat night. 

image

 

Does that cycle use the immersion heater? 


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Colin
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@webcmg Mine was set to 10, I think it's the threshold before it starts charging the cylinder again assuming it's within an enabled time period. I lowered it to 8 because some days we didn't lose more than 8ºC so it missed charging up the cylinder during the cheap nightly time window.

We don't use the separate immersion heater.

 

image

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webcmg
(@webcmg)
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Joined: 6 months ago
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@colin Hi Colin, we've certainly reduced our Kwh usage for the hot water based on the settings. We now currently use between 3-4 Kwh per day to heat the water. 2kwh in the morning and 1-2kwh in the afternoon depending on usage (n.b. flat rate tariff). The anti legionnela cycle seemed to reach the required temperature when I checked this week which is also good. Thanks for your help. 

SmartSelect 20220616 070624 VRC 700

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