JohnMo

Been charting my usage over the winter months, but have remained on E7 throughout. Looks like I loose about 1kWh per day during the charging process During November I managed to utilise 80% of all usage, via the low tariff (16p) and the remaining 20% came from the higher tariff (35p) December we had 2 weeks at around -7 deg, but still managed to 72% at low rate January was 74% Last few days has all been low rate as the suns been out, and is charging the battery during the day Have tried during the winter period, several operating regimes 24/7 running on WC, batch charging the floor, weather compensated flow temp and fixed flow temp running on a thermostat, to effectively batch charge over the 7 hours of E7 and as long as required in higher tariff period by utilising the battery. From an energy (kWh) used per day perspective, the fixed flow temp on a thermostat option, seems to work out best for our house. The fixed flow temp is set at 35, with heat pump rarely actually getting to that point, due to the mass (approx. 47 Tonnes) of floor to heat up, and by the end of the heating period the heat pump is producing around 33 degs (ish). No cycling of the heat pump (except defrosting), one single run per day of between 8 and 12 hrs (so far). I do get a CoP impact, but not enough to worry about generally. From a monthly cost perspective, when compared to gas I have been around £100 cheaper in Nov and £40 cheaper Dec and Jan. When compared kWh to kWh per day, on normal rate and E7 rate, I am saving between £60 and £100 per month during the heating season. Pretty good day today - At midnight last night, I still had 40% battery charge. -2 over night up to 7 degs during the day and the sun is out, but due to be -5 tonight. This morning floor finished heating at 8.30am, cylinder at 50 degs at 1pm, battery fully charged again at 1.15pm (by PV generating around 4kW). Currently hot water cylinder being topped up by diverter and heat pump running (forced override on the thermostat) to do an hour or two floor charging for free. Expect zero high rate electric today, same as yesterday. But on Thursday wet all day forecast so expect zero solar that day.

Bit of an observation, from the drawings the drop looks quite big, so do you need a structural design to ensure your design is robust enough? To bolt through box section, you would normally have a sleeve over the bolt, the sleeve fits inside the box section and is just slightly shorter than the overall box section dimension and acts as a compression piece, so you do not compress the box when all is tightened

You don't mention zones, if you have any or many or just one, that will make a difference, nor do you mention how you heat radiator or UFH or a mixture? Generally LLH, PHEs add to required flow temperature required from the heat pump which all have a negative impact on CoP. You need to seperate the design of the heat pump and use of PV, they may be related but different subjects really. Hot water cylinder are easy, size to suit your usage, specify a 3m2 coil, done. I heat a 210L cylinder in around an hour from a 6kW ASHP. Have a PV diverter to dump excess solar into water during peak generation times. Anti freeze in the grand scheme of things is cheap. Antifreeze valves require no antifreeze solution in the heating medium. But if you are away and have a power cut, when it's cold, you may have to top up the system to get it going again. Antifreeze doesn't have that issue. I just add about 20% antifreeze, to get freeze protection down to about -6, limited impact on performance...

The guy that did my air test did the MVHR commissioning for building regs sign off. Should be able to find someone close to you - Google is your friend. Install is pretty straightforward, just be methodical, long single runs, lots of tight bends are not good. Locate the unit centrally plenum for flow and one for return

Do you really need it? I consume most the contents of the cylinder each day, so zero need. If you you take days to consume a cylinder worth if hot water maybe you need it. Heat Geek have a good write up, worth a read.

Have two units, one through timber stud wall, the foam was taken through the wall, the other unit goes through ICF and that had a cast in place hard plastic duct, with a stub on the inside flush on the outside.

Not really bound material, just gravel in a grid, I would ask if your planner in the local council is happy?

Just looking at your basic plan, the external walls are all over the place, with sticky out bits for the kitchen and ensuite. Could these lines be simplified? Makes build the house easier, reduces heat losses etc. Do you really want a utility room at the front door?

Best thing we did, was to go to the beach with the drawings, a tape measure, and a stick. Draw the house in the sand, full size. Made adjustments until it felt right. Did this a few times until completely happy.

Hi do I you have a photo of the setup. If it is operating that way you will be getting a rubbish CoP, just because are alway heating the cylinder to around 50. You may be better routing the UFH direct to the floor manifolds

Other than cost, what advantages other than to confuse guests, do the switches bring to the party. The lights go on or off, you still seem to have to touch the switch.

Final update Been faffing about in the background, to get the house heating and summer house heating to work together, one is high inertia (thick screed UFH) and one very low inertia (low volume fan coil). Final solution is, have dumped WC altogether and now flow set to a fixed demand temp of 35. That suits the fan coil in the garden room and a slow batch charge of the floor. Observation the heat demand of 35, the discharge temp from the heat pump never actually gets to 35 for the 10 to 12 hrs it runs, at the moment. Most days it gets to about 33 by the end of the heating cycle. Zero cycling occurs, except for defrosts. There are two thermostats, one in house and one in the garden room. The house thermostat can call for heat and changes set point of an electronic UFH mixing valve, the garden room thermostat can call for heat. The electronic mixer valve in the house, is selectable to two different adjustable set points, currently set to either 35 Degs or 27 Degs. The 35 Deg set point ensures mixer is fully open and zero mixing occurs. The system volume isn't large enough to support the heat pump driving a single fan coil on its own, so the house floor is always available to act as buffer via the 27 set point on the mixer valve. Batch charging is simply controlled by a single room thermostat, with a hysterisis set to 0.1 - at 00:30 it is set to 20.5 (starts heating if at or below 20.4), at 07:30 it is set to 20 (switches heating off when above 20.1) and at 12:00 it is set 19.5, makes sure heating doesn't restart. DHW heating is timed to allow heating any time between 1pm and midnight.

And what advantages does it offer over a £2 light switch, except to confuse your guests. Aren't you just trying to reinvent the wheel, with an expensive price tag and bunch of functions you have get the instructions out every time you think about using them? Not sure you list anything a decent thermostat doesn't do.

Best thing I ever did was to through my Solic 200 in to the bin and get Cool Energy diverter. It has timers so you can time boosts if you want, can control two immersions if that's what you have and also tells you what its doing and has done in the past.

Funny thing I just looking at ESBE website vrb140, actually a 4 port, takes a flow from two sources and can mix or isolate and take from one or the other. Not sure how you would control

The wall shouldn't be structural, so just a diversion between two room. Just says bodge the way they did it.

Has it always been like this? Did anyone touch or maintain the system prior to the noise starting? When I had air in the system the flow meters bounced about - I would start by bleeding the system.

My only gripe about MVHR is that you have a base flow rate and it can only upwards with a boost. When it does boost, it boosts across the whole house. There doesn't seem to be an automated lowering of duty point when humidity levels are low. Have seen on MEV systems they can have modulating extract terminals based humidity, the MEV unit is constant pressure controlled, so if the extract terminals close in because no one is home, making humidity, the unit almost stops. If the house is full of people showering ect the unit speed is increased as the terminals start to open. No idea why MVHR doesn't feature the same sort of logic, it's just a matter of running supply fan to match the extract duty, to keep the system in balance.

That was a good answer. It does demonstrate that following building regs ventilation flow rates does over ventilate, by quite a large margin. I think I need to turn my down my flow rates further. Currently at 0.3 ACH.

Often thought about UFH control. Most systems are controlled on flow temp via a mixing valve, and with with room thermostat(s). Most use a mechanic mixer, some use an electronic mixer. With an electronic mixer, there is normally a temperature of probe on the supply pipe - but could you just look at water return temperature and then modulate the flow into the system via the mixer. So run a set return temp and modulate the flow temp going in. My thoughts are, it may give faster warm up times. It may automatically compensates for how much heat given off by the floor; flow/return dT changes, as floor to room dT changes, shows up in the return temperature moving up or down, so could you have more stable temps? Anyone any thoughts?

Comparing with a humidity controlled MEV and humidity controlled inlet devices, so it only just ventilates enough, how does it compare? Trouble with MVHR is it runs 24/7/365 at a rate of 0.3 to 0.5 ach. Ventilation is whole living space, need it or not. If you didn't need the ventilation on, although recovering lost heat, it recovering need less lost heat.

PV, battery and ASHP can be a good combination, if the heat pump does cooling, summer cooling is free. In winter depending on the angle of the PV you can offset some running cost of the ASHP in the late part of Jan, Feb, March, Oct and early Nov. But paying someone to do it, even with grants, costs can stack up. You may be better concentrating on insulation and airtightness to reduce size of heat pump. MVHR for ventilation to reduce your ventilation heat loss and recover the otherwise lost heat.

You can still use the same principles of cascade with a normal MVHR unit.

Remove type 1, replace with soil or sand, form the deck with 3 to 4" posts, post-crete into the ground. A lot to be said for SuDS. Lots of hard landscaping no use for rising water levels and residential run off into rivers.