@technogeek Thanks for providing the link - Graham's argument makes perfect sense, and it was nice to understand the logic of why Quiet Mode exists.
Samsung 12kW gen6 ASHP with 50L volumiser and all new large radiators. 3.645kWp solar (south facing), Fox ESS inverter.
Solar generation completely offsets ASHP usage annually. We no longer burn ~1600L of kerosene annually.
@transparent That illustration suggests an 8-10 double sockets job to me, after all, that is still only 4 sockets per wall and two for plug in sensors or detectors. Regards, Toodles.
Toodles, he heats his home with cold draughts and cooks his food with magnets.
@transparent Back in the seventies, a new building was being constructed in my department and I was asked by the architects for comments on the suggested room layouts and design. As a technician, I was aware that one double 13 amp outlet in each room wasn’t going to cut the mustard. I looked at the plans and noted that there was one proposed drop in conduit to a double socket per room. I commented to them that as these were offices for staff who would be using a desk lamp, a dictation device and a tape recorder (early 70’s) at the very minimum, there ought to be at least two double sockets per room placed on opposite walls so placed that the tutors would have a choice of which end of the room was used to place the desk.
Back came the reply from the architects that this was an extravagance they could not condone! I then suggested that if the drops were so placed, they would supply power to two rooms per drop and that by placing them at opposite ends of the room for alternate drops, each room could have four sockets for very little extra cost. They adopted my suggestion but even then, the tutors all needed extensions leads to plug in a myriad of other low power devices. Unfortunately the heating had also been skimped on and we ended up having to use one wall socket per room for a fan heater! Regards, Toodles.
Toodles, he heats his home with cold draughts and cooks his food with magnets.
Owning an air source heat pump (ASHP) is a constant learning experience. We’ve installed plenty over the years, but only one with a full energy monitoring system.
Normally, we rely on manufacturer data from their various apps and online portals—which, let’s be honest, never quite tell the full story.
Recently, I installed a Vaillant aroTHERM plus 10kW three-phase ASHP at my own home, complete with full monitoring hardware, so I can finally see what’s actually happening with the system. I deliberately went for an oversized unit because—well,my gut told me to. Come summer, we’ll be linking the house to an older building, so at the moment the ASHP is nearly twice the size it could or should be?!
The main house itself is a new build, with 285m² of ground floor space and an additional 15m² mezzanine above the master bedroom. About 50% of the house has ceilings averaging 3…5 metres high, so there’s plenty of air to heat. It’s super-insulated, has high thermal mass, an airtightness of 1.9m3 /(h·m2 ) @ 50Pa and no heat recovery or trickle vents.
yes, no MVHR! I did consider installing an MVHR system, especially since our home is fairly airtight, and recovering up to 80% of the heat from outgoing stale air sounds like a great idea. But every home is different, and how it performs depends on how it’s actually used by its occupants. Instead, we stick with good old-fashioned Stoßlüften (shock ventilation)—turns out, simply opening a window at the right time works brilliantly, especially when combined with the building’s thermal mass! Our windows have always been, and always will be, wide open first thing every morning while the beds are made, and again, probably kept on the night latch every evening. Fresh air, no faff! That said, I wouldn’t recommend this for everyone. In fact, in my day job, I strongly advocate for installing MVHR to maintain good air quality in buildings. It’s an excellent solution for many homes, especially those that are well-sealed and occupied in a way that limits natural ventilation opportunities. But for us? We’ll keep doing what works!
We’ve got underfloor heating (UFH) throughout with 100mm pipe centres buried in 98mm of beautifully polished concrete. This not only provides a fantastic heat store but also makes for a seriously nice-looking floor—because why shouldn’t heating be both efficient and stylish?
The older building we’ll be linking to adds another 80m², with similar U-values. However, it won’t match the airtightness or thermal mass of the main house and will require radiators. This brings the total footprint to 380m², with a calculated heat loss of 6.86
17 W/m² for the main house (17 × 300m²) = 5.1kW 22 W/m² for the older building (22 × 80m²) = 1.76kW Total heat loss = 6.86kW
So why did I go bigger than necessary? Because my gut said so.
We did all the usual heat loss calculations, Vaillant did theirs, and even our merchant confirmed the numbers. Every bit of logic pointed to a7kW systembeing the perfect fit. But despite all that, I went with my instincts and opted for the10kW unitinstead.
I’m always the first to say,“Trust the numbers”—but this time, I didn’t.
The system was installed in December, with the heat monitoring linked on the 17th Jan, meaning we now have nearly a full month of data—aside from the 36-hour blackout courtesy of Storm Éowyn, which apparently decided we didn’t need electricity for a while. That little hiccup aside, the data is starting to paint a very interesting picture of how the system is actually performing.
The initial results, well they looked promising, with the first week averaging a COP of 6.1 with a mean outside temperature of 7°C. Given that this cold wee country averages around 10°C over the year, that’s a very encouraging start.
Over the following three weeks, we’ve seen a 3-4°C drop in outdoor temperatures, in addition to tweaking the system to see how I can achieve the best COP for domestic hot water (DHW). As a result, our overall SCOP (30-day average) is now sitting at 5.3—still respectable, but there’s plenty more experimenting to be done!
So, back to the oversizing…
Today has been the warmest day since installation, and the charts and graphs on Emoncms Heat Pump Monitor make for some interesting reading. In addition to the increase in outdoor temperature, I did two things yesterday:
Dropped the heat curve from 0.3 to 0.25
Set the system to Eco Mode
The result?Eco Mode has nearly doubled the DHW COP—but is this purely down to Eco Mode, or is it just theeffect of the warmer outdoor temperature? Something to investigate further.
Another interesting—or slightly concerning—occurrence is that the ASHP appears to be switching off or at least cycling for extended periods. Between 2:10 am and 5:10 am this morning, the heat pump was basically off.
Is this a sign that the system is too oversized for the milder weather, or is it simply a normal response to lower heat demand? Will adding the extra 80m² of building help balance things out, will the high thermal mass and system volume just deal with it or have I set myself up for a troublesome time?
Only time will tell whethergut instinct beats maths… but for now, the system is running well, and the learning continues!
@aaron I’m curious as to how you achieved the designed pipework to achieve a workable volume in this installation. Especially since you have oversized the HP. LOOKING AT THE PIPEWORK ONLY- for a 300sq M floor area I can’t imagine things working without a significant surplus of water built into the system. So Aaron this is a really major achievement worthy of a fuller understanding of what you have done. What measures have you taken to create a balanced system?
More-so than attributing the system performance to your gut feel, you have balanced the system offload and system output. So it suggests a much deeper understanding.
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