Eco-refurbishment of our house

[mikepepler]

A while ago I asked for advice on heating systems for a house we were buying:
http://www.powerswitch.org.uk/forum/vie ... hp?t=14471

Well, we're in it now, and the work has started. So far just making sure all lights are low energy, fixing the water butt and insulating the cavity wall: http://peplers.blogspot.com/2010/08/ins ... walls.html

Next on the list is:
- stove with boiler installed: we've gone for a 9kW Woodwarm Wildwood, with split saddle and roof boilers, which will run central heating through a pump and hot water by thermosyphon.
- solar thermal on the roof
- upgrade loft insulation (after the plumbing is all done)
- hoping to get a small amount of PV on the roof for a DC system (I already have all the kit, just need to get them on the roof).

I'll post more pictures on my blog as the work progresses.

Thanks to everyone who gave advice while we were planning it all out!

[CountingDown]

Good work Mike.

One of the things we did was check the power use of our fridge / freezer - our old one was a ridiculous power hog.

[mikepepler]

Well, we didn't have a fridge, as there was one included with the place we were renting, so we had to get one. To save money we bought one second hand for £35, but it turned out to be a bit erratic, with the thermostat swinging widely between 0C and 15C!

So we had to quickly get another one... The most efficient ones (A++ or something like that) are about £400, which was too much, but we got an A+ one for £160, and also it's a larder one, with no freezer compartment, as they're more efficient if you don't need the freezer bit.

The next one to tackle is the freezer - we have a small old one, but it is at least a chest freezer (a tall and narrow one). I've found that it seems to be using more power in our utility room than it was in the garage at the old house, but that's probably because this room is actually a small conservatory, so is warmer (in the summer at least). I've already got bubblewrap round the non-radiator parts of the freezer to insulate it. It's currently plugged into a power monitor (and has a thermometer inside it), logging the kWh usage over time, so I'll see how it gets on before deciding if it needs replacing or not. The interesting thing is that it would have taken me a lot longer to spot it was using more than it should if we didn't have a whole-house energy monitor...

[emordnilap]

The next one to tackle is the freezer

Sundanzer, Polarfrost and Sun Frost are three names that come to mind.

[mikepepler]

Probably a little out of our price range!

Anyway, I established today that the problem is the room temperature - 25C!!! It was a steady 17-18C in the garage at our old house. I left the door open this afternoon as I was working at home, the temperature dropped, and so did the power consumption. I also cleaned the radiator (condenser) at the back, and improved the airflow to it. I'm wondering if I could set up a solar powered fan to improve ventilation on sunny days... Anyway, it won't be a problem once we get to cooler weather.

[Andy Hunt]

Sounds great Mike, I'll be interested to hear more about your DC pv system when you have it up and running.

[mikepepler]

Sounds great Mike, I'll be interested to hear more about your DC pv system when you have it up and running.

It won't be as fancy as yours Andy!

I can tell you the kit, as I already have it:
Charge controller:
http://www.morningstarcorp.com/en/sunsavermppt
and as a backup an old (non-LCD) 30A version of this:
http://www.morningstarcorp.com/en/pro-star

Battery:
http://www.barden-ukshop.com/rolls-24ht ... -911-p.asp

PV:
Two of these:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0550043485

Inverter:
http://www.thepowerstore.com/product.asp?ID=1808

So step 1 is to get the panels on the roof, instead of sat in a window, where they've been in rented houses in the past. At the same time, I'd like to add a few more PV panels, perhaps getting up to 200-250W. With the small inverter I have I can then run the central heating pump and/or the solar thermal pump if the power is off. Could maybe run the fridge too, for a short while, as long as the start-up surge isn't too high.

Step 2, when money becomes available is:
- buy more batteries, to set up a 24V system with higher capacity, My charge controllers already auto-switch between 12 and 24V, and at the higher voltage then have the capacity to take double the amount of PV. (I'll have the PV installed so I can rewire for 24V later on)
- buy a 1 or 2kW sine wave inverter, running off 24V, as this is more efficient than 12V.
- wire the new inverter into the house mains, with a switch to take us off grid and onto the inverter (I've asked an electrician about this).

With these plans in mind, I had the insulation installer put a core vent under the stairs, where I will put the batteries and box them in, thereby getting ventilation for the hydrogen produced during charging. I wasn't sure this was necessary, but after getting the Rolls battery, I found you can hear it bubbling when charging!

[Andy Hunt]

Sounds good!!

When you get your 24v inverter, if it has a connection for 240v shore power you can just wire that into your consumer unit fusebox. Then your switch to switch between mains and inverter is simply the switch on the consumer unit. This has the advantage that in a power cut, your system will switch over to the inverter seamlessly.

[mikepepler]

When you get your 24v inverter, if it has a connection for 240v shore power you can just wire that into your consumer unit fusebox. Then your switch to switch between mains and inverter is simply the switch on the consumer unit. This has the advantage that in a power cut, your system will switch over to the inverter seamlessly.

I'm not sure I understand. Does the grid power go through the inverter and into the house? How many amps do you need for transfer? The Victron range seem to have 16, 30 and 50A, but the top end cost quite a bit!

[Andy Hunt]

When you get your 24v inverter, if it has a connection for 240v shore power you can just wire that into your consumer unit fusebox. Then your switch to switch between mains and inverter is simply the switch on the consumer unit. This has the advantage that in a power cut, your system will switch over to the inverter seamlessly.

I'm not sure I understand. Does the grid power go through the inverter and into the house? How many amps do you need for transfer? The Victron range seem to have 16, 30 and 50A, but the top end cost quite a bit!

The 1.5kW Powermaster one I have is basically designed for use on a boat, and so it has a 240v A/C input to receive 'shore power' when the boat is docked. When there is 240v present at the connections, the inverter automatically feeds it straight through into the ring main and charges the batteries at the same time. Simply disconnecting the 240v with the switch on the consumer unit makes the inverter automatically flip over to the batteries, as if the boat has cast off to sea. The inverter acts as a UPS in this way in the event of a power cut.

[contadino]

The next one to tackle is the freezer - we have a small old one, but it is at least a chest freezer (a tall and narrow one). I've found that it seems to be using more power in our utility room than it was in the garage at the old house, but that's probably because this room is actually a small conservatory, so is warmer (in the summer at least). I've already got bubblewrap round the non-radiator parts of the freezer to insulate it. It's currently plugged into a power monitor (and has a thermometer inside it), logging the kWh usage over time, so I'll see how it gets on before deciding if it needs replacing or not. The interesting thing is that it would have taken me a lot longer to spot it was using more than it should if we didn't have a whole-house energy monitor...

All freezers (and fridges) have a climate rating at which their power usage is measured. I can't remember them all, but they are usually a letter or two. At the high end of the temperature range is ST - Sub-tropical = best operating between 15 and 25 degrees, T - Tropical = designed for ambient temperatures between 20 and 35 degrees, etc.. There are others designed for lower ambient temperatures, but I don't know what they are. Some brands publish this information, others don't which is a PITA.

Worth checking out before deciding where to site a freezer, and before buying one.

[mikepepler]

We now have our stove in and working! I'm still trying to catch up on writing it all up, here's the details of the stove installation:
http://peplers.blogspot.com/2010/09/eco ... stove.html

and if you're interested, the chimney sweeping, which was done before installation:
http://peplers.blogspot.com/2010/09/eco ... imney.html

Still to come is a post on the plumbing, and another one on solar water heating (which is being installed on Monday...). Loft insulation is after that...

[adam2]

When you get your 24v inverter, if it has a connection for 240v shore power you can just wire that into your consumer unit fusebox. Then your switch to switch between mains and inverter is simply the switch on the consumer unit. This has the advantage that in a power cut, your system will switch over to the inverter seamlessly.

I'm not sure I understand. Does the grid power go through the inverter and into the house? How many amps do you need for transfer? The Victron range seem to have 16, 30 and 50A, but the top end cost quite a bit!

The 1.5kW Powermaster one I have is basically designed for use on a boat, and so it has a 240v A/C input to receive 'shore power' when the boat is docked. When there is 240v present at the connections, the inverter automatically feeds it straight through into the ring main and charges the batteries at the same time. Simply disconnecting the 240v with the switch on the consumer unit makes the inverter automatically flip over to the batteries, as if the boat has cast off to sea. The inverter acts as a UPS in this way in the event of a power cut.

Yes several inverters have this facility, but it cant normally be used to back up the entire house, owing to the limited output from the inverter.
The transfer switch or feed through facility normally has a greater capacity than the inverter, but still less than the supply to a house.

If you wish to use the automatic changeover facility, then the load must be less than the inverter rating, even with the mains present.

Most such inverters also charge the battery from the grid whenever available, this is very useful for a boat as it saves running the engine for battery charging when in port.
Might not be suitable for use with PV since the battery will kept charged from the grid, and may not utilise the PV output.

I would be inclined to use a manual changeover system.
Have a dedicated ring circuit connected only to the inverter.
Have sockets on this circuit next to the grid supplied ones, in key locations.
Plug the fridge, freeze, heating pumps, into the mains or grid as required.
Connect a mains input to the inverter, but leave this turned off normally and charge only from the PV array.
Turn on the mains input only in case of prolonged or regular powercuts, in order that the battery may be fully charged from the grid,ready for the next power cut.

[RenewableCandy]

When you get your 24v inverter, if it has a connection for 240v shore power you can just wire that into your consumer unit fusebox. Then your switch to switch between mains and inverter is simply the switch on the consumer unit. This has the advantage that in a power cut, your system will switch over to the inverter seamlessly.

I'm not sure I understand. Does the grid power go through the inverter and into the house? How many amps do you need for transfer? The Victron range seem to have 16, 30 and 50A, but the top end cost quite a bit!

The 1.5kW Powermaster one I have is basically designed for use on a boat, and so it has a 240v A/C input to receive 'shore power' when the boat is docked. When there is 240v present at the connections, the inverter automatically feeds it straight through into the ring main and charges the batteries at the same time. Simply disconnecting the 240v with the switch on the consumer unit makes the inverter automatically flip over to the batteries, as if the boat has cast off to sea. The inverter acts as a UPS in this way in the event of a power cut.

Dang! We're 1.6 kWp! Do PowerMaster do a bigger one for boats (e.g. for Rrrussian millionaires' luxury yachts and the like)?

[Andy Hunt]

Not sure I understand your question Candy. The inverter can provide 1.5kW @ 240va/c, but it can take about 1kWp of solar PV as it has a 30A solar controller @ 24vd/c.

Powermaster do a 3kW inverter, not sure if it has a bigger solar controller on it though. You wouldn't get your FIT payments going down that route though.