Bruno

Just a quick update to this topic as I got my brand new Vaillant aroTHERM plus 85 installed and started up yesterday and today. I was able to get the installation as I wanted, including the possibility to use the wood burner together with the heat pump. I'm waiting for the "Internet gateway" VR920 to be able to access the system from the Vaillant app. I got the VRC700 controller, which is a bit "outdated" if I'm honest. Not having a color LCD in 2021 as a minimum is really strange... I was hoping to get the sensoCOMFORT VRC720 but the price is a bit high. Anyway it serves the purpose and now I'm starting to take some daily registers to improve overall efficiency.

Thank you. Insulation is being improved. But I need to definitely replace at least one radiator, in my bedroom. Even today with high temperature it heats far less than the others because it's at the end of the circuit. This will only get worse as I'll decrease the water temperature. I'm actually considering a ventilated unit for this specific case.

Of course. This is the smallest radiator I have, but the connections are all the same, the only difference is being on the left or right side of the radiator.

I'm currently using high temperature aluminium radiators, and looking forward into replacing them with others, suitable for working with ASHP. All the current radiators have 600mm water input/output connections. Most low temperature radiators have smaller distances (some much smaller). Because the plumbing is already built into the walls, I must keep the 600mm. Are there any adapters for this situation? Looking good is a bonus as not all radiators can hide the plumbing.

Are you happy with electronics? There are a few cheap projects with arduino which can help you. Basically you need a solar cell and a resistor in series, than a way to measure the voltage drop across the resistor https://create.arduino.cc/projecthub/jeffrey2/measuring-solar-radiation-with-arduino-f741ac Or search "arduino solar intensity"

A bit off topic, but different country yet same situation. I got a quotation for replacing my windows 3 years ago. This year we have incentives for these improvements (up to 1500€ for each home) so I asked for an update of the quotation. Guess what: almost 2000€ more expensive.

"B minus" ? To be honest I think that the evaluation was too nice. My windows are of terrible quality (just ordered new ones), the blinds and its straps have had direct connection to the outside, I didn't have any renewable energy source at the time of the inspection, ... And the only recommendations on the certificate are the walls and ceiling insulation. I'm not thinking in doing it (not for now at least), but I was trying to understand how people do it ?

I live in an apartment and I got it an "energy inspection". The resulting "energy certificate" mentions classification B- and the points to improve are mainly inside walls and ceiling insulation. The ceiling is more or less clear how to do. But what about the walls? If I was to insulate every outside wall, how does one does it especially regarding the windows frames? I mean, apart from the materials, I am having some difficulty to understand how is this insulation done regarding existing window/door frames, central heating pipes, electrical cabling and sockets, etc. The piping and electrical part is more or less obvious, but what about the walls? Is this doable in an inhabited house, or is it something to consider only when building/remodelling? (eg, the house is totally empty)

I didn't know that, but it seems clear from your (and others) previous comments that I have very significant heat losses from the cylinder to the shower. I will have to work on improve that for sure.

OK, some further updates, I was able to get in touch with the manufacturer of my DHW cylinder. According to them, it's a 150l copper cylinder, with a 10m copper coil, inside diameter 22mm. That gives roughly 15m of water volume, but only 0,7m^2 of surface area, although it's copper which has greater conductivity. In fact, the cylinder does heat up quite fast with now, so on that part it's not an issue. If I add 3m of external connections, that goes roughly to 20l of water for the DHW circuit. Do you think that this is enough for the heat pump to work? The minimum flow indicated on the specifications is 540l/h.

True that. I guess we'll see, for sure I'll try both ways. First I need to find an installer who wants to take my money ?

Insulation of windows with XPS boards is a common recommendation here. Especially the "box" above the window where the blinds roller work. These are direct connection to the outside in both cold and dirt ? I did that myself a few weeks ago, most of my neighbours already did it (or paid someone to do it for them) with very good results. I'm extremely happy with my results, especially after also finding a cover for the blinds "strap".

As I said before, mostly due to the cold sensation in the bathroom. And according to your descriptions, It seems clear that I have significant losses in the pipes, I definitely need to improve that. That's how we use it now, with the wood burner: we start the fire, the cylinder gets hot, everyone showers, the cylinder gets cold. Tomorrow we heat it again. That's how I intend to keep it even with the heat pump.

The DWH cylinder is the same we have now, 150l which is enough for everyone to shower. If I believe the temperature indicator on the cylinder, the DHW is heated to 60°. At that temperature we definitely need to mix some cold water. But I will need to look into improve the insulation of the hot water circuit, for sure ? I will. Thank you.

Yeah, that's what I will do next. It also helps that I've read and asked a lot (thank you all), so now I also know a bit better what I want. It depends, I was discussing that today with one of the suppliers. In summer it's totally fine, even more than enough. But in winter it isn't: - on one side, my wife and kid love to shower with water which makes their skin turn red ? - on the other side, often we want that very hot water because the house (specifically the bathroom) is a bit cold. I hope to improve that with better insulation and the ASHP running permanently, but anyway I want to be able to choose ?

Hi @J1mbo again thank you for your reply. I did contact Vaillant Portugal and they replied quite fast about this. They didn't use the word "approved", they said "with experience and certification for heat pumps installation" To be honest, what I'm missing the most is to be able to talk to someone who is not "interested". I got very few replies to my quotation requests, but every one of those was contraditory in solutions and ALL of them want to share the DWH and radiator heating in some way. Here's a short list of what I got: - 2 suppliers quoted a 9kW, other a 12kW and other a 15(!)kW heat pump. The first said that my requirements are perfectly fine with 9kW and that everything above it is too much, the last said that 15kW is ideal so that the heat pump has enough reserve for very cold days. - None of the quotations have a diverter (3-way) valve. One wants to connect the DWH cylinder in series with the radiators, 2 of them wants to connect a secondary circulation pump to the buffer tank so that 1 goes to the radiators and another goes to the DHW cylinder (their justification is that this way I can get DHW and heating at the same time, I then told them that 40-50º might not be enough for DHW and they said "sure it is"), the last I have absolutely no idea how the system would work but there is no 3-way valve in the quotation. - At least one of the quotations has no integrated DWH control, I would use a clock and a thermostat to control the respective circulation pump. I don't want this, are we in 1990? ? - One has no buffer tank, other has a wrong buffer tank (specifically the Vaillant aroTHERM mentions clearly a 40l buffer, they quoted 100l), other has an hydraulic separator, other has both (!). - Some cared about my request to integrate the wood boiler, others didn't. - I specifically indicated that the ASHP needs to be placed on an outside wall as I can't have it on the ground (I live in an appartment). I did not see any mention to wall supports on the quotations, plus the 15kW heat pump I was quoted weights 170kg ? What a mess ? Anyway I will update this if I have more news.

I found the installation manual from Vaillant. I'm pretty sure I would be able to do this myself ?

Mine is probably not a "heat pump cylinder", I suppose it's designed for using wood burners. But you gave me a good idea, I'll contact the manufacturer and ask if they can provide the coil surface area ? I'm also looking into that, thanks. I'll replace 2 radiators and distribute the sections in the remaining ones.

Indeed. I've been asking locally and the thing with COP 1 with high outside temperature seems to be utter BS. But the price is just good. Damn. What about the current DHW cylinder, do you think that it can be used with the HP? Looking at the aroTHERM documentation it always mentions their own uniTOWER cylinder...

No, I live in Portugal, sub zero is really, really rare. Not more than 10 nights per year, for sure

It wasn't me. It was the salesman who told me that, I was just quoting him.

And what about this, what do you think?

Yes, that's considered. But according to him, that would be used to trigger the start of the HP when there is a temperature drop, not to control it directly. And that would of course heat both the DHW and the radiators. I tend to think that too. But as I don't know the "guts" of how an HP works, I can't debate. The price is really attractive for this HP (70° outside temp, A+++), but I can't get them to install it as I want it to, after all, they're the experts...

Currently I have a wood burner which circulates hot water (please see first post). When the water in the burner reaches 60° its circulating pump starts to run, feeding hot water to the DHW cylinder. When the DWH cylinder's thermostat reaches the setpoint, it diverts the hot water to the radiators. It's normal to have the temperature in the wood burner to keep increasing (a little of course) while the DHW is being heated as the circuit is small and little heat is radiated. In 30min the setpoint temperature is reached. But of course I don't know what's the return temperature. But it seems that most DHW cylinders have much more water than the amount you can use. Apparently mine hasn't, it only has a small hot water circuit through it (around 3m he said). What the salesman told me is that, because there is only a small amount of water in the DHW heating circuit, the return temperature would be pretty much the same and the HP can't handle that.

That's what I thought too. But about the DHW cylinder, do you think he's right? As the circuit from the HP to the the cylinder and back would have only some 3-4m, can't the HP handle this? (having the "same" temperature in and out while doing DHW)