ReedRichards

Sorry to interject myself into this topic but I'm now wondering how programmable these A/C units are, when used in heating mode. Can you programme different temperatures at different times and on different days of the week, as you can with a central heating programmer?

I had been looking at what was on offer on the Appliances Direct website. The units there seem to be predominantly R32s, I had not realised that there were a few R290 units as well. Hence my question about F-Gas certification.

I'm wondering about getting one of these units myself but don't I strictly need an F-Gas certified installer to put it in?

Every autumn, field mice take up residence my loft to spend the winter; I have no idea how they manage to get in. I trap and remove them but it's a constant battle for a few months. They like to chew on the pipe insulation but have never touched the foil-covered type; I use Kingspan Kooltherm. The downside to this is that it takes a long time to install, making it a DIY job rather than something you could afford to pay a tradesperson to do.

When trying to heat my water with excess solar electricity I tripped the over-temperature cut-off on my immersion heater on many occasions. But I was always able to remove the cover, press the little rod-like button and it reset. Why was yours no resettable in the same way?

That's your suggestion, I think, not something the OP said. How about a volumiser if you don't like buffers?

Yes, it would work but the heat pump is more likely to cycle if it is only heating part of your house.

A section of my central heating was badly designed so that return water from zone 2 can flow backwards through a radiator in zone 1. I tried a double check valve but that made a lot of noise whenever water was being pumped through it. So I moved on to a single check flap valve which is silent except when it closes; closure causes water hammer in some pipes buried in a wall. I think the problem is that these pipes were not secured so move and bang against a beam. I tried fitting a hammer arrestor (a flomasta bell-shaped type) but it only worked for a week. What I seem to need is a flap valve with a slow-close mechanism. These appear to be used in North America for basement sump pumps but they are hard to come by here and anyway they don't look to be up to the standards required for central heating with pressurised water. I can't find anything that seems to be appropriate for use in domestic plumbing. Any suggestions?

They are typically no more noisy that the flue from a condensing boiler but they are subject to restrictions on noise, unlike boilers.

If the water coming out the shower had dropped to 30 C I'm sure your kid would have let you know! The only logical explanation I can think of is that the sensor is right at the bottom of the tank, for some unknown reason. That's pretty much was @jothis saying.

No, it's terrible, but I am struggling to think how an installer could get this wrong.

I don't think any specialised equipment is needed, just a lot of time and patience. If you can't get your house up to the desired temperature then whatever output temperature is being called for is set too low (for that particular outside temperature). Eventually you should be able to map out what output water temperature is needed for the range of outside temperatures you encounter. Then you set your weather compensation ("Water Law") parameters to match that.

Well it looks like it's Load Compensation as well as Weather Compensation if it boosts the output to get the house up to temperature. Heat pump manufacturers seem to delight in inventing their own terminology for processes that are well-establish and named for gas boilers. And no two heat pump manufacturers use the same terminology, as far as I can see.

I remember the days when you got 1000 W multiplied my time (In hours) for your kWh. At only 100 W no wonder the energy companies are raking it in!

I switched from oil to a heat pump and up-sized the radiators at the same time. Almost all oil boilers are just on/off so if you just oversize the rads but stick with an oil burner you will heat the house more rapidly and increase the frequency at which your oil burner cycles. That's neither good for efficiency nor good for the longevity of your oil burner.