Marvin

Hi @evekell A quick check to see if the bottom door seal is working is to pour a small amount of cold water on the outside of the door when it is closed and see if it goes into the house. I have done this with ours before now by using a COLD kettle and pouring a trickle about a foot from the bottom of the door, onto the door and frame, across the entire width of the door from the frame one side to the other. If the bottom seal is damaged it will leak If the door has been raised in the frame too high it will leave a gap between the bottom of the door and the seal and leak. This is a simple and easy thing to cross off the list of potential problems before doing any serious work. Good luck M

Hi @SteamyTea No smart meter. Energy used by ASHP goes through a separate meter first which only logs amount used. PV is already monitored to turn things on and off with CT clamps measuring the power to the grid. Extremely rare to supply power to the grid in winter even if PV working at full capacity. The Watt/hour level only peaks when doing serious cooking. Home background level is about 600w ASHP is in weather compensated mode and I wanted to see if the hot water is still adequate in lower temperatures.

Hi @SteamyTea Hope your well... This is the start of a test I am trying to do during the winter as this is the high use period. The heating is programmed to be on permanently and will be on until the spring (a few degrees lower in the night but still on) The hot water is programmed to come on when the tank temperature is below the 'on' until above the 'off' levels. the spread being 5.5°C, However I will stop that happening on occasions (when the outside temperature is lower than today, with no sunlight) to see what happens. You have made me think about it and I will record where the hot water temperature starts from in case it is below the level of 'demand' when it starts. Other poster had been discussing what happened to the house temperature when the heat is diverted to heating up the hot tank. I realised this would be affected by the outside and inside environment and decided to record the result when possible.

19/10/2025 8.30 am test: House temperature when heating hot water: During this test no major actions in the home were happening that would effect the results. Outside Temperature 11°C Weather no sun/raining/25mph wind - gusts to 30mph. Home temp 22.7. Hot water tank 205 litres Buffer tank 36°C Hot water starts calling The difference between hot water demand turn on and turn off is a rise of 5.5°C Hot water reaches temperature in 35 mins Home temp after hot water demand is 22.7°C Buffer tank 35.3°C Home temperature during 30 minutes after hot water heating finished stayed at 22.7°C In my opinion the time taken to bring the hot water tank up to temperature is suitable in duration (we are using low fan speed) and does not materially effect the home temperature when the outside temperature is 11°C.

Hi @JohnMo and @HughF Thanks for your thoughts. Yes I have lifted the sensor temperature to 42 degrees. However this is not the temperature of the water in the majority of the tank because of the sensor positioning. Reasonable hot water temperature and consumption in this bungalow. Thanks for your concern. Definitely over 45 degrees in majority of the tank when set at 42 and over 60 once a month.

This is the sort of thing that is my aim. I just need to adjust the ASHP controller to the right settings.

I cannot find the hot water set points so have adjusted the temperatures in the weather compensation section. M

My problem has been that the hot water temperature has been set at 40 but it doesn't actually kick in until about 36 which is too low. So on the odd occasions when the temperature is below 40 and there is shower demand the water is not hot enough. However because I have the system running on low speed mode it takes a while to reach 40 so rather than enter the weather compensation part I will alter the hot water temp diff to 2 and the stop to 2 and see how that works out. Unless anyone has a better idea.... Thanks Marvin

Hi @dpmiller I think I have worked it out. I use weather compensation so the hot water temperature is defined there.

Hi @dpmiller Yes I can bring it to user mask but then what? I have previously entered the engineers code but I cannot access U01

We have no app connection....

Hi @dpmiller Hi Its the CE-iVT9 and it's the set point? (to be clear - the point at which the water in the hot water tank rises so much that the ASHP stops heating the water in said tank)

Hi I need to change the set temperature of my hot water tank using the Carel controller. I have the engineering code but cannot find the location where you set the hot water temperature thermostat. Its slightly too low at present. Does anyone know the system well enough to guide me?

Also there were industrial scale trials. But look at the big scale and the fact that they couldn't easily regulate the output. https://www.pure.ed.ac.uk/ws/portalfiles/portal/8885379/Energy_from_Waste_Reuse_of_Compost_Heat_as_a_Source_of_Renewable_Energy.pdf The mix to obtain the warm reaction needs to be live. Mixing grass cutting, green (not evergreen) stuff and an amount of shredded sticks works quite well because of the mix of aeration, moisture and bacteria. I expect to start a pile next week and will supply info. I only use this as a way to produce great compost of garden waste. (not vegetable waste either!)

This is a subject I have researched and worked on in detail. The production of heat is caused by the bacteria reaching between 37 and 54 degrees centigrade with the right amount of oxygen and water. Far below 37 it just rots and takes ages. Far above 54 and it dries out and goes crispy. In huge commercial trials this has been hard to duplicate for several reasons. Although you can calculate the heat potential, controlling it, is nigh on impossible. Information, and my own trials, show that the mound needs to be at least 1 cubic meter and live material. Yes the compost goes better in summer but you can insulate around it in winter, but then it can over heat and the bacteria dies. Also it needs to be mixed correctly.

A concern would be the starting up of the ASHP if it was frozen. I think you may have to wait for the compressor to warm to above 5C before you should start it otherwise is causes excessive wear?? I think that is for 12 hours continually above 5C. I think that's why the ASHP circulates at night and has a heater (warmer??) in the unit that comes on in cold temperatures?? Well that's what I understood.

That makes 2 of us. Also there is a slim chance that the place freezes up, power goes down and 10 thousand ASHP's go pop at the same time and I will be the last on the repair list.

Hi @Great_scot_selfbuild My air source heat pump stops heating the radiators at the lower temperature and then heats my hot water tank at a higher temperature. Once the hot water tank is up to temperature it then reverts to the lower temperature. This is all achieved using a 3 port valve. On a highly insulated property like we have, we have never noticed the building temperature drop whilst heating the 204 litre hot water tank. That said, we don't have any baths only showers.

Replacement bearings arrived.

Yes true. Also a requirement for fire escape in some cases.....

Today I found out that our DOMUS HRX2 MVHR which was installed in 2017 was not running correctly. Upon inspection it appears to be the fans in the unit are not working properly. Based on the excellent information, from @Steve W and others above, I am hoping to avoid paying about £800 for the 2 new fans and I am gambling that the bearings are shot and have ordered the SKF E2.608-2Z/C3 8 x 22 x 7. I never thought of this and will have fun trying to get access to the unit in my loft. During the renovation/build, my wife insisted (may I add against my better judgement and being a waste of money) that we have openable windows! Because of this we will now be able to have an airflow although the building whilst I attempt to fix the darn thing. I will never hear the end of this!

The fall on the inspection chamber would be the wrong way. They are designed to flow 3 into one not 1 into 3! It may be the requirement for a rodding point and a place to see if the water is dissipating and the drain is not clogged up. I have accesses each end of my surface water soakaway for these reasons. I would have offered two Y junctions with the straight on rising to a rodding point. Good luck M

We built/renovated a smaller property than we could afford so we only considered cost engineering on each task on a value for money angle. It was enough doing the work without financial pressures. I also have a feeling that any pie chart would be very personal to the actual building and only be indicative to any building. M

Hi @kbsoloman I don't expect that the blockwork was put up without reason. More pictures will help. Or draw a rough sketch showing more info: how long is the wall to the left of the picture. Whats behind the wall How high is the ground the other side of the wall Otherwise tricky to comment. M

How much are the gaps 5mm? 30mm? Not sure if you are saying if you can get temporary access to both sides when filling? In my humble opinion non-compressible material should be used under every vertical stud position as a minimum. I always used a dry sand and cement mix 3:1 just damp enough to hold together when squeezed in my hand to pack gaps like that. Packed in tightly in gaps and allowed to set. Good luck M.