Marvin

Depends of amount of pipe available. Not easy if pipes go into screed but often easy when timber joisted floor.

What causes the water to go through the Bypass radiator? temperature or pressure or ? Where is the bypass radiator? in the bathroom or ?

Where in the building is the buffer tank? In the loft?

Don't hang about. Carefully put suitable wooden chocks either end of the radiator between the bottom of the radiator and the floor. Don't force them in, just use enough thickness to be firm. If your really worried squeeze silicone in where the fittings are off the wall as a temporary measure as well this will help to stop it wobbling. M

The MVHR units can be quite big. Ours fits through the loft hatch. We rolled 400mm of loft insulation over it and around it.

How deep are the joists. How deep is the hole.

It suggests the head may not screwed down to the body correctly. You have to rotate the head into the groves of the body before screwing the collar. (the groves stop the head rotating before the collar is screwed up It may be that the head has not warmed up yet. The head has an expansion vessel in it which pushes down on the top of the pin which closes the valve. the expansion vessel takes time to respond. The rad valve may be colder than 15C and need to warm up. The product is faulty. Many other reasons that clever people will come up with. Good luck M

https://www.coolingpost.com/uk-news/roof-mounted-heat-pumps-on-trial/

Sounds like the set temp for the defrost to kick in is high

Hi @Beelbeebub Yes it works, but by 'reasonable', what is required are radiators with a larger surface area than for boiler heating so the lower temperature is dissipating over a larger surface area thereby giving off the same amount of heat. Luckily I didn't believe that our renovated home would be as thermally efficient as it is and had installed larger radiators than calculated when fitting the boiler before converting to the ASHP. Where we did have any cool spots i replaced a single panel radiator with a double. there are many upgrades you can do: P1 also known as Type 10, is a type of radiator with 1 radiator panel and no convection fins. K1 also known as Type 11, is a type of radiator with 1 radiator panel and 1 set of convection fins. P+ also known as Type 21, is a type of radiator with 2 radiator panels and 1 set of convection fins. K2 also known as Type 22, is a type of radiator with 2 radiator panels and 2 sets of convection fins. K3 also known as Type 33, is a type of radiator with 3 radiator panels and 3 sets of convection fins. As @ProDave says above be careful about cost efficiencies. Ours were achieved by the fact we were using expensive bottled gas to run the old boiler and we have PV that supplements the electricity used so the savings for us are good. Good luck M

could that cause any issues to the retaining wall??? Yes. But it might not. The devil is in the detail.

And my advice is that it can technically be built but it may depend on planning rules, building regulations, ownership of the retaining wall, property deeds, and everything else I'm ignorant of. As my brother used to say 'It's not if, but how much.' Good luck M

Hi @iSelfBuild Items you may wish to consider.. Soil mechanics! Load baring capacity of the Soil Slip plane Heave Full design details of existing retaining wall (survey may be required) Existing services. Old and new drainage. Localised flooding Leylandii hedge is known for its shallow but wide root system, depending on the soil and the variety of leylandii. Permitted development rules. https://www.gov.uk/government/publications/permitted-development-rights-for-householders-technical-guidance Who owns the retaining wall Conversation with the neighbours Undermining the stability of the existing retaining wall whilst your gym vibrates as you pump iron🤣 Yes this is the problem. Without a drawing with accurate dimensions (not a scaled drawing)written on it, with both horizontal and vertical distances, ideas given could be excellent or Ballox and pictures of the walls really help. (is the retaining wall vertical or leaning towards your drive at the top?) In my opinion a raft foundation is more likely to cause heave or lateral pressure on the retaining wall. Good luck Marvin

You can do either and I have done both but skimming with Thistle Multi Finish Plaster will give you a better end result in my opinion.

A photo or 2 would help. I'm surprised that it takes so long.