JohnMo

Normally they have an anode to stop corrosion, when there is carbon steel in a cylinder. These are replaced every couple of years. Maybe the anode has depleted and you have plenty of corrosion going on.

If you have intermittent fans, just replace with dMEV fans, they run at a low rate, almost silent, they will pull the air through the trickle vents and give cross flow ventilation. Then replace the normal trickle vents with humidity activated ones, so you vent through the trickle vents when needed. Least impact on heat loss, no need to pull your house apart to install.

Unless you have super small piping or a huge ASHP there is no noise from piping, from what I have experienced.

If you need that much PV should like your insulation and airtightness needs some looking at. I installed gas, and moved to ASHP soon after completion. Wanted cooling as we also have big windows. I would look at insulation, airtightness, do PV (about 3kW min) and ASHP, coupled to UFH. Plus heat pump cylinder. Ventilation I do MEV with humidity activated terminals in wet rooms, and with humidity activated trickle vents. Least amount of ventilation and only operating when required. Almost no running costs, no filters.

Progress today, piping all completed and system cleared of air. Unit running. Have reverted to WC for house and set back to an older heating curve that worked fine. That should lower ASHP flow temp be 5 degs, from current settings. Just need to check the garden room gets up to temperature. To do Seal opening through wall Insulation to be added to all joints Final run around all the bottle vents to ensure all air out of system. Paint the aluminium taped insulation to match woodwork.

Fan coil being installed in garden room to replace UFH, which really didn't work well unless at flow temperatures. Which wasn't an option with the ASHP and the main house heating demand. So Christmas eBay search led to me buying a Myson iVector MkII fan coil 1.2m wide. This unit can do heating and cooling and has a variable fan cut in temperature, so should allow me run weather compensation. Unfortunately the unit needs to placed on the opposite side of the summer house to the existing water entry point. So instead of running pipes internal, have decided to run them externally. Some photos of progress Unit wall mounted Cover installed The unit I got is a 4 pipe fan coil. This unit has a dedicated cooling and seperate heating heat exchangers. The heat transfer area of the combined heating and cooling HE's is about 50% larger than a 2 pipe fan coil. Have piped the two HE's as a single unit. I am using a Salus self balancing actuator to balance the flow rate through the fan coil. Have started the external piping using 15mm Hep2O and 25mm wall thickness insulation. The insulation to aluminium tape covered to keep mice away and UV to stop sun damage. The pipes sit on metal brackets 40mm off the ground and are galvanised banded into place.

My ASHP did something similar (not cool energy) just after I started to do DHW with it. It changed modes from heating to DHW and just stopped waiting for something. I switched off and on again, never done it since.

My pallet shed is just on concrete blocks levelled. Our summer house is on heavy concrete 3x2 slabs. Or do screw piles - no concrete

Very unlikely to carbon steel, will be copper or stainless. Towel rad strong suspect

Biggest trouble with dMVHR is they have a small area of influence, and do not give whole house ventilation, unless in every room space (and/or are reversing and well planned). The Tempra dMVHR isn't the most silent vent system from what I can gather. They are not really that efficient. Not sure your current plan will be very good at actually giving a well ventilated house. In all likelihood your bedrooms will be very stuffy and there is no ventilation, the trickle vents will do very little to help on their own. For trickle vents to be effective, they need a fan in a wet room to pull air through them. I would do dMEV, something like a Greenwood dMEV fan is silent, draws next to no electric, couple that with humidity activated trickle vents, you only ventilate as required, so you are not wasting energy.

Very good point If you have unbalanced flow, the MVHR efficiency drops like a stone. A 90%+ efficiency, could easily drop to 50% or less, which is almost a waste of time running, as you are using twice the electric of a MEV system. As @IanR say run when you need, but do so with balance flows. Or just run all the time, at very low flow rates. Get a CO2 monitor stick in your bedroom and monitor. If you go over 1000ppm at night increase the rate. If you settle under 800ppm slow the rates down.

Lower pump speed, give less system head (pressure) for a given flow rate. High pump speed give a higher head for a given flow rate. When you close a lock shield you increase pressure drop at that location and decrease flow rate, a pump running at too higher speed, will just find somewhere else to dump the fluid and keep causing imbalance. Higher the pressure the easier the water can push it's way though small gaps. For an efficient system (least pump power), you need as little restrictions as possible, while having system balance and so allowing lowest pump speed.

That's just a normal mechanical one

Or buy everything before you complete and get the vat back anyway. £1.5k to do the paperwork why bother, you can get a heat pump for that if you shop around

Why - there is no requirement to be fully built, on a self build. Do yourself favour and read all the requirements. No EPC required either, because you already comply with building regs.

Been looking into IR recently. From what I can tell Room or person heating isn't as quick as made out. It's very directional You are not heating the air, just the room furniture, walls, floor and people, so can be operated at slightly lower temp than radiators. Unless very well insulated it's going to cost a fortune to run. Even at lower room temps, you are are paying 28p per kWh. If you have high blood pressure and a few other conditions - one site was up front and said to look at other heating technology as IR was not suitable for you. I spent my money on a fan coil heater instead.

Have read up, other good boilers are Intergas, Atag, both do weather compensation out the box. https://theintergasshop.co.uk/content/189-why-hot-water-priority-pdhw-is-the-reason-s-and-y-plan-should-be-banned

If you have wired a d set up as S/Y plan, you are stuck with one flow temp. WC will not work correctly as you need a high temp to heat the cylinder. You need to change the wiring to X plan or priority hot water. This switches the boiler to 2 different flow temp setting. Your UFH will have a mixer valve as the flow temp will be different from radiators, so on a fix temperature. Not really of smart thermostats, so will leave that for others to comment. Most are just dumb on/off units with WiFi. If it was my house. X plan on boiler, using only boiler controller to do WC. Heat pump cylinder so I could do DHW as low temperatures. No zones. Viessmann boilers are good, but need to be plumbed and wired as per their instructions, to get the best out of them.

If the design temp for the radiators 60 then that's the flow temp that you need. With mixer at 40 deg flow your boiler will need to deliver 50 degs or more anyway. Good thing is with a return temperature to boiler below 54 you will be condensing.

So long as the fans run as required, at a constant rate (we exchange air at a rate of 0.3ACH) and you have a manual boost button, nothing more is really required. Auto boost, time clocks, not needed. In winter the humidity is likely to be too low rather than too high. For example today outside is 2 Deg and 99% percent humidity, inside 20.5 and 39.5% humidity. Last time I used boost was because we had 10 people in the lounge. Check/clean with hoover the filters every 6 months, replace with new every 12 months. Forget it's there the rest of the time.

Just reread, yes missed that. The dream unit, can be set to run at a fixed temp, job done. Then leave to look after it's self.

I have around 50 to 60L in total. Recent change. In an attempt to run the system hotter to get better performance out of the summer house UFH without overheating the house. I made the following changes. Added a thermostatically controlled ESBE mixer and pump to house UFH - this is generally dropping flow temp down to 29 from 34 so spends most its time less than 50% open, it also close fully. This in effect reduces the system capacity. Added a buffer across the supply and return piping, this acts a min flow valve, with 50L capacity. UFH in summer house is still rubbish, so now installing a fan coil, which generally requires around 35 Deg flow temp. Things still a little fluid, but will look to operate, as such 1. Single house thermostat 2. ESBE mixer, if no heat demand, flow temp 29, if house thermostat has heat demand, flow increases to 35. 3. Single flow temp of 35 degs for heat pump (may alter but will see how things go) 4. Fan coil, Salus self balance actuator to give a 7 deg delta across fan coil and shut off flow as required.

Think these products have a small place, but the property has to heat heat like an open window. Then anything is better than nothing. But anything else don't waste your money.

If you heat a buffer at a fixed temp say 30/35 and have another means of heating DHW and/or use the buffer to preheat water going to the DHW cylinder, shouldn't be be too bad to run. Just how things used to be a decade ago (or more). They are basic heat pump, and they are cheap. The inverter ones are R32 and internet connected (smart) but the functionality is no different to the basic unit, apart from modulation.

Pretty much how S and Y plan work. Manufacturer add lots of good features and the UK plumper f"**s it all up, by using S and Y plan plumbing.