MikeSharp01

Almost complete on the HP install all flushed through, pressure tested everywhere and filled for testing (still need the inhibitor) Powerup tomorrow, would have been yesterday but weather stopped us because you have to take the lid off the HP to make the final electrical connections if you want a BMS connection. Anyway the final challenge is to fit the temperature probes into one or both of the pockets in the UVC. There are two pockets one at about 50% height and one at 75% height and there are two probes. One (A) looks after the immersion heater and the other (B) looks after the Heat Pump - sends Domestic Hot Water (DHW) data direct to the HP presumably for the HP to know it has got the water to the required set point. The tank is quite dumpy and 200l so I assume it makes no difference as the tank probably does not stratify so well that it matters. Have I go that right? To help me out I have used the top pocket for both so if it does stratify I am working on the hottest water and I can read the temperature from the BMS and its reading the same temp as the immersion limits.

An old Architect of my acquaintance once told me that if you cannot get your hand into the crack then you do not need to worry about it, hopefully one of our friendly Structural Engineers will be along shortly with a view.

Just another thought, we kept the service void in the utility room and had we not done so we would have had problems with mounting things like threaded inserts through the VCL used for things like munsen clips and the like.

If you use a wood screw it punctures the membrane and fills the hole with the shaft so provided the thing it is attaching is down tight there won't be any leaks. So we didn't bother with anything other than screwing down tight generally, we got a 0.2 on the PH scale for our air tightness and there must be 1000s of screw holes through the VCL all clamping down wood, but only wood. As @saveasteading points out anything else will need special treatment. I tended to mount them with self sealing screws, such as the ones used to screw down roof sheets, or mounted them on a strip / square of mastic tape to fill any holes. Your worry here is jacking as your screw might push the two layers apart slightly but in the end the screw will fill the hole makes won't it. You have to plug the holes! We did cover every staple with a tape square and fastidiously marked damage for repair if we made any.

Thanks @SimonD I will get some loctite 55 - try and copy the pro's eh.

Yep here are a few. The total depth of the thread in the socket to the lip is 16.87mm the thread length of the barrel plus the washer is 15.76. Also on the return there is no lip more a radius to the pipe diameter inside.

Just tried it and the washer is floating when the barrel is tight and it does not look like it has a flat face at the bottom of the socket just a small lip!

That makes sense going onto the fkt face valve o it's the same for the female set into the machine is it - neat.

I am about to make the final water connections to the heat pump (HP). I want to use a 28mm barrel to the HP connecting to a flat face valve them a swept 28mm bend then onto the flexi to the flow / return pipes running alongside the HP. I was wondering what method to use the joint the barrel into the HP. Liquid PTFE, straight PTFE tape or a more old school method. I prefer the liquid PTFE but am happy to take advice from experts.

Which model is that?

Hopefully! Yes the balance / trade off between flow rate and delta temp I have done calcs based on 3, 5 & 8 K against our limiting UFH (pressure drop wise) loop. Our pump can deal with 7m head and at 3K it will be running at 6.3m head drop.

Technically you are correct the flooring company say 27 but I set the max at 24 in my calculations to see if we could get the output, I think we can, and have a good safety margin - the floor is second only to the windows package cost wise.

Feels way to high for our floor. Got to get my head around this WC thing we need to keep our slab interface to the wooden floor maxed at 24oC so a max water temp of 26 perhaps. What was your floor surface temperature?

So your heat demand should be 10W/m2 or there abouts. Unless you have a huge house or live in the Arctic circle you probably need less than 3kW.

I cannot imagine that the heat pump can overheat the cylinder so I have discounted that issue. My motivation for wiring as it is was just protection for the immersion but also so I could add the PV control later. I looked at the details of your system and thought I might give it a try at some point. There are several other probes in the tank pockets - one for the heat meter, one for the heat pump and one for the BMS monitoring. There are so many safety systems in this system my failure mode analysis (FMA) figured all would be OK. Here are the bare facts: The immersion has a stat of its own that limits the water temperature it can achieve. The immersion has a over temperature cutout should it get that far. The tank has a temperature and pressure safety device. The BMS probe has an upper limit setting that can raise an alarm at a chosen set point (85oC variable) The 24V system has the over temp cutout and the temperature control cutout I could put them in line with the immersion - one or both, but doing so would limit the ability to use all the PV up to 80oC when you wanted only 50oC from the standard cycle. I did consider taking a feed from the immersion live connection, at the immersion and using the BMS logic to tell me if it is powered up when it should be off but have discounted the need for this as the protections above mean it is not really needed. I did figure the Heat Pump would do the whole job but having an immersion as a standby makes sense to me.