HughF

We have a post war ('46) end of terrace, three bed, one bathroom that's block-50mm blown cavity-block construction with render and full internal plaster. We have double glazing (10yr old) and we currently have moderate condensation on the inside of the windows most mornings and during the day in the winter. The house is occupied by two people, one works normal hours and is away from the house 8-5, the other can sometimes be home all day. We heat it to 20 deg all winter long and keep the windows shut because we don't want to let that precious heat out. Our windows do not have trickle vents. I'm working on more air-tightness upgrades (re-fitting the windows that the cowboys installed, insulating and bagging the suspended floors) so now need to think about ventilation. I understand that full MVHR isn't worthwhile on an old property such as this, and that there are heat recovery extractor fans that can be installed in places like the bathroom and kitchen. At the moment the bathroom walls are like a river in the winter time (north and west facing external walls which I'm going to marmox board soon) so that needs to be addressed. I do have access to the loft so I could install ceiling vents in the bathroom and the three bedrooms and some sort of 'fan box thingy' in the loft. What should I be thinking of doing to improve things?

One of the good old Carrier/Kingspan units: https://www.ebay.co.uk/itm/224969293878?_trkparms=amclksrc%3DITM%26aid%3D777008%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D20201018205123%26meid%3Da69f00f8c4904591b17f02593f6f3faa%26pid%3D101286%26rk%3D1%26rkt%3D1%26mehot%3Dpp%26itm%3D224969293878%26pmt%3D0%26noa%3D1%26pg%3D2380057%26algv%3DWatchlistVariantWithMLR&_trksid=p2380057.c101286.m47999&_trkparms=pageci%3A7ac95cb8-d05f-11ec-ac42-46fb8d9d075d|parentrq%3Aae0376491800a4d496de3f0ffffe89a8|iid%3A8 No idea if the programmers are available any more, and beware that the rating seems pretty generous (A7/W35)

Good prices from World Heat for their off-the-shelf 120 and 150ltr offerings, and super responsive on the email too.

Understood, so your demand side (room stat, zone valve, zone pump) and supply side (call for heat volt-free terminals, ASHP circ pump, buffer sensor) are working together. That seems sensible.

Really? Well that wasn’t the answer I was hoping for 😂

My service valve outlet is 400 below the front lawn, I’m looking to pull a new 25mm mdpe off this, run about 5m then bring it up inside my new porch (having gone under/through the porch footings). From there, a 25mm mlcp riser will go up to the bathroom and feed the rest of the house from there. The current 20mm mdpe goes into copper, somewhere, which then comes out of the kitchen slab. This copper is weeping at the ends and is due for replacement. Any reason why I shouldn’t stick with 400mm deep off the service valve? I’m not in the north of Scotland, and we’ve never since 1946) had the service valve freeze up. I’ve got a digger, but it seems a total faff to go to 750 deep when the week point will always be the service valve depth.

I’ll write a better response this evening when I’m in front of my laptop…. If I forget then @mention me

@Chriswillsthese popped up on my radar too, Care to pass on details of the UK representative? cheers…

Why don’t you do your own heat loss and rad sizing? I’d absolutely not trust a grant money hoovering, new van driving, ex DG salesman to get that right. LG units are cheap, seem to have a nice controller, but have slightly iffy looking specs at higher output temps from what I’ve figured out. The 5, 7 and 9 only push their rated figures at A7/W35, the high flow temp numbers are a bit rubbish, all three delivering the same output iirc. Midea look decent but they won’t sell direct, and their data needs derating a bit also. New rads are always a good idea, moving up to type 22s allows you to drop the flow temp down to efficient levels. It’s a dead easy swap size for size, complete no brainer not to change up to them from 21s or 11s.

Banki/crossflow would be my go-to for this low a head. Do you have anywhere on your land where you could build a sluice and make a feed pond?

Buy from wherever you feel comfortable. We all have a different appetite for risk, mine seems quite large You're unlikely to get any warranty if someone installs it who isn't 'manufacturer approved' - or some similar rubbish. Personally, I'd just buy it and find a friendly, decent, local plumber to hook it up. If your technically minded enough, the installer settings are pretty damn simple on most of these things, just a few temp and time settings. You basically can't screw them up.

Play with the 'your system' tab on the spreadsheet and have a look at what machines around the 5-6kW bracket will cover the heat load (you can specify the UVC size in this section too). Beware, some manufacturers ratings in the model numbers don't really add up in reality (cough, Midea, LG, cough)... Midea won't sell you one anyway, so you can discount them. 5kW ecodans pop up on eBay fairly often, usually with the 150ltr pre-plumbed cylinder package.

I’d fit type 22s as a matter of course, this whole ‘get by with what you’ve got because we can just turn the flow up to 55’ mentality that lazy specifiers seem to have is half of the problem with domestic heat pumps here on the UK. Specifiers should be designing for a 45 deg flow when using rads in my opinion. But yeah, basically just fit the biggest type 22 you can in each room and you’ll be sorted. If the rooms are too hot just turn the flow temp down and watch the cop rise. As for the walls, the heat loss calc has an entry for ‘custom’ rather than ‘from data entry’ where you can enter a specific U value. As you are in a flat, put every room as ‘heated room above’ on the drop down box.

So the nest turns on the heat pump and then shorts out the call for heat lines too? If I’m reading your message correctly.

Just bought a chinese three port diverter, I'll let you know what it's like when it shows up. It was only £20 I initially went looking for anti-freeze valves, having objected to paying for caleffi 108601's - AliExpress had some for £18 each that 'start to dribble at 6 and open fully at 1' - for that price I couldn't say no. It turns out the supplier has a pretty good range of actuated ball valves/diverters.

Just got off the phone to Dave at CE, super helpful with my queries...

Attached, the unlocked/unhidden version of the Freedom toolkit. They were giving this to anyone who asked for it, off the back of a youtube video showing how it worked, but that video has now been taken down. 2124036581_2021FreedomHeatPumpstoolkitV3.3forallinstallers-Copy.xlsx

A-7/W50 is a much harder task than A-3/W40…. Much harder. Rad sizing at 50 deg flow is Easier, but I’d try and size for 45 if you can.

I used the one from freedom heat pumps, which does have a few issues in the output data for the midea units and in the rad sizing sheet (rad sizing is designed for a fixed 50 deg flow temp, even though the performance sheet allows you to change the flow temp). I designed for a 21 deg room temp at -3.5 outdoor temp. It rarely gets that cold where we are and I’m oversizing the unit ‘a bit’.

I used the one from freedom heat pumps, which does have a few issues in the output data for the midea units and in the rad sizing sheet (rad sizing is designed for a fixed 50 deg flow temp, even though the performance sheet allows you to change the flow temp). I designed for a 21 deg room temp at -3.5 outdoor temp. It rarely gets that cold where we are and I’m oversizing the unit ‘a bit’.

Now you mention that, I remember seeing this in the manual. I couldn't figure out if the flow temp was fixed when you did this, or whether the weather comp was active and nudged the flow temps up or down. I feel a visit to Grimsby might be on the cards to have a detailed look at these controllers

That’s exactly the way it should be done, yes… how one does that in practice, with the units in my price range, I don’t know (yet)

Understood, thanks. I’ve seen some units from salus that appear to do just what I want.

It's the programmable setback stat that I'm looking for - I want that to happen automatically at a preset 'bedtime'.

I'm going to try and get away without a buffer and just use an LLH, as I'm short of space. Really short of space...