MikeSharp01

Ouueeer a Sewer!

Pretty un intelligent of the machine, but given everything sounds right - it never gets to set point. There is something else that Graham says in his video - if you set the tank temperature to 48 then the water in the tank can vary between 43 and 50 implying that the hysteresis is 7 degrees so although the set point is 48 the system turns off when it gets to 50 and back on when it gets to 43. So if the flow temp is too ow it never gets there!

I also found this in the manual: "We normally aim to heat the cylinder within an hour, if you want to decrease the reheat time you can do so by pressing the DHW mode button, this will show a picture of a bath and will run both heat pump and immersion heater at the same time." Which should solve your immediate problem. Presumably the legionella cycle is done with the immersion heater as the HP won't achieve that. I did think of a test to see the difference between the heat pump set point and the tank temperature. Get the DHW cycle running and after an hour, assuming it has not reached the 48DegC temperature back of the 48 temp setting by 1 deg at a time until the system recognises the tank is warm enough. This will give you the difference (delta) and you can then adjust your main flow temperature up to overcome it. Curiously there seems only to be one flow temperature setting in your system '2021' there is no equivalent in the heating group 3XXX so maybe the thing just runs at maximum until the temperature is reached. If this is the case then the temperature you get from my experiment above is the max the system can reach in current circumstances.

Do you think your system looks like this?

Looks like you can turn on the immersion heater to get the bath problem sorted. Not sue that 2Deg C is sufficient difference to get the tank to ever reach the 48Deg C figure, has it ever reached 48 with the 50Deg setting? As the actual temperature out of the ASHP will be much lower by the time it reaches the tank coil almost no matter how much insulation you have. So you need a few more degrees on that setting otherwise it won't get to temperature and switch to heating. 18Kw is loads so you should have no problem delivering serious quantities of HW to the tank but the temp must be high enough to overcome the losses in the system.

Cannot see any pictures but the text is useful.

Do you have a systems diagram of your setup that may have been left by the installer, first or second but second preferably?

No you should have two temperature settings for the water flow out of the heat pump, one high - for heating the DHW and one lower for running the radiators. At any given time there should be heat in only one circuit, DHW tank coil or Radiators, never both.

New to me but otherwise sounds like plan.

Actually belay that - I just found it does exist in their range but not available from my supplier - so will have to go elsewhere for that.

Agree they all look approximately the same and largely do the same thing but you need to ensure that you can get all the functionality you need from the range available. We are just going through this and in three locations I need 4 double boxes and a single to achieve what I need (2x13A, 2xCAT6, 1x5A, 1xTV aerial and 1x twin Audio plate) depending on range I can combine some of these or not and then there is the switches. Makes a difference to the socket real estate and so the range choice you have. EG MK do not do a Wifi controlled wall socket and have no plans to make one. Scolmore 'new media' has every sort of plate except white so while I should be able to achieve a smaller config with that it won't match white switches. Its more of a mine field than it first appears.

2.5 m/s is a more common upper limit for air velocity generated noise so provded you are below that you should be OK.

Yes but not on external doors.

There is a relatively well known, although I cannot find it right now, piece of research which says that there is a sweet spot in the problem solving, information gathering space which says that there comes a time, after the sweet spot, where you are managing so much information that it starts to damage you ability to solve the problem. So watch out for that, but otherwise enjoy!

Again I think the units are quoted per fan, so you need a bit less - 75L/s plus you must work the system so supply and extract are handling the same volume otherwise you will get a rise in pressure across the house. You need to decrease the supply or increase the extract - naturally ensuring you stay above the statutory (Building Regs) limits.

We are looking at this right now and we have been told, 3 sources and here, that you should aim at the unit running between 50 & 65% of max capacity in normal mode.

Found this quote on Google: but the associated link does not work. "ZIPLEVEL® is a high precision pressurized hydrostatic altimeter. It works much like an aircraft altimeter that measures the weight of the air above it except that ZIPLEVEL does not use the atmosphere to measure elevation."

You do wonder don't you!

PS there is also the old adage of keeping the flow velocity in any duct below 2.5ms for reason of noise.

I think you only need to do the extract side of the system as the supply has another fan and to keep things in balance will deliver the same volume of air (so you will need to adjust it down to 57). So each side can be independent and that will sort of halve you extract pressure drop to 90 (ish) much better and your supply at about 140 but each fed by their own fan. Least I hope I have that right as I have always assumed there are two systems and the pressure unit ratings are for the two independently not added together.

How did you work this out - did you include the incoming / outgoing ducts feeding fresh air in and stale out to the atmosphere. Also remember that runs in parallel don't just add up.

but are tidy targets like anything else fixed down the location of which is known!

any chance the plaster board is supported as shown?