Posted by: @econonsense

↑

@cathoderay Hi I have a thermostat display in the house, it may have settings in it, the main controllers are in the shed. To be honest, I have no idea what most of the settings are so I'm loath to play with them. My water was back to normal temp this morning, but the outside temp is quite decent today. So it seems entirely dependant on how cold it is outside.

I have to wonder about the temperature inside that shed. Earlier you noted that it's a pressed steel shed. Did the installer add a generous layer of internal insulation (including on the door)? Insulated hot water cylinders still lose heat. I've recently had a heat pump installed with the hot water cylinder, pump, etc in what was the coldest room in the house and it's now become the warmest room. A steel shed, however, will leak all that heat unless it's extremely well insulated and free from draughts.

Good point @johnr - but it also sounds like a good location for a substantial storage battery and inverter(s).

The heat generated by the inverters will help raise the internal air temperature. 😋 

I'm hoping @econonsense will avail of us of some photos soon.

Here's a good example of how to build a hot water cylinder shed starting with a well-insulated base.

Yes @johnr - a well-built shed...
... although there's quite a few contractors brought in to achieve that result.
They're not cheap!

I'm less happy about the amount of insulation around the PEX pipe runs which went 15m under the suspended floor of the house.

The text says that's a 25mm Maincor MLCP.
So we assume that is the external dimension of the pipe itself.

Measuring by eye, I'm guessing the insulation jacket has a wall-thickness of around 13mm.

If it were me, I'd want to use a 19mm wall, especially over that length.

I'm also puzzled why the author favours such a large DHW tank if he already knows the existing gas boiler will be changed for a heat pump.

When he gets around to choosing a Heat Pump at a later date, it will need to be one which can cope with raising that water to 60°C for 10-mins during the anti-legionella cycle.

As he writes later:

I hope others here will read that article.

@cathoderay The pipe run is only around 2 metres and insulated, is it not more likely the system is never getting to temp? I cant imagine the losses in such a short run could be so significant. The runs through the attic space are far longer, up to 25-30 metres, but again all insulated I'm told, I've not been in the loft since they insulated it as its very shallow, maybe 1 metre high in the centre with a load of rockwool to climb on now.

I had the main company get back to me today, they are arranging a local company to come and look at insulating the shed and changing the thermostat / controller which they say they have had a lot of problems with.

Cheers

@transparent Hope these help

Posted by: @econonsense

↑

they are arranging a local company to come and look at insulating the shed and changing the thermostat / controller which they say they have had a lot of problems with.

So was your installer a major (national) company?

FWIW I could easily arrange for a 2m external pipe-run to lose 10°C if I wanted!

• I'd make sure rainwater could flow between the inner pipe and the insulation, and then drip to the ground
• I'd used open-cell insulation which could hold water within it
• I'd put no insulation on it as it goes through the outer wall of the house
• and instead of using an outer protective sleeve, I'd pack mortar around the pipe to absorb heat into the fabric of the wall

2: If they've packed lots of fresh Rockwool in the attic space, did they take care to relocate any electric cables above it?

Or have they buried them below the insulation, thereby compromising their current-rating?

Please excuse if I am mis-seeing due to my poor eyesight but, those vertical pipe runs look to have a considerable number of very tight clips compressing and thus compromising the insulation. Regards, Toodles.

Oh great: photos!

I can't see where the DHW pipe run enters into the house,
but I thought you'd appreciate my first observations

And that pipe insulation doesn't appear to have sufficient wall thickness.
It needs to be 19mm.

And here are my annotations for inside the shed (plant room)

@transparent Hi these are all very valid questions, the passage through the wall is inside a 100 or 125mm plastic pipe, each pipe insulated within it. Re the integrity of the insulation, I haven't checked.

Also regarding the loft insulation, I don't know, I haven't been up there since they did it as I have a severe back problem and emphysema which is why I qualified for the grant. My guess is they just buried everything.

I did take the precaution of running most the electrical cables along raised joists when I rewired this house. It is very old, still had black and red twin and earth cables most of which had been butchered at some point.

Even 10 degs of thermal loss wouldn't account for this though, on a good day its 45 degs, on a cold day its 25 at best. I am in a rural seafront location, open fields over 300 metres between me and sea. I suspect its simply to cold in the mornings for the WH to overcome it in the heating cycle which I think is 1.5 hours.

@cathoderay Hi cathoderay, I am always impressed by the abilities of people like yourself on this forum and I can see why you are interested in how AAA works. I can only give my rather unscientific observations. Although I am very happy with it, it's not perfect, partly because I have programmed target temperature changes into the HP, to take advantage of 3 periods totalling 8 hours of half price electricity and avoid 3 hours of 50% higher cost electricity, on the Octopus Cosy tariff. I raise and lower the target by 1C and have the HP switch off for the 3 expensive hours. This usually results in around 4 or more hours of HP pause at night and again in the morning. AAA recovers the room temperature adequately, but I saw some peaks of higher Flow Temperature than I thought necessary. So I limit these peaks to 40C or 45C by switching to Ecodan Quiet Mode 1 or 2 depending on the weather and go back to normal unlimited mode if temperatures are going below zero. But these adjustments are just me trying to get a higher efficiency, and are not necessary for comfort or reasonable economy.

Like your house, ours is slow to hear and cool, having all concrete floors. Our kitchen/living room is 15 metres long of South facing patio doors, so we get massive solar warming, and I have to turn down the AAA thermostat from say 20C to 18C as soon as the sun comes in - turning it down by less does not quickly stop the heating. Likewise, it's best to turn it back up before the sun goes down to reheat the floors. I hope these experiences are of some help.