I have 3 air source heat pump proposals. 2 of them give a flow temperatures, the Heat Geek one doesn't. I watched the HG video on flow temperature, but that didn't answer my question (or I didn't understand it....)  Can someone tell me why HG doesn't give this number?

Thanks

Therefore, can any members please provide some advice on my air source heat pump installation journey, I live in an old stone built detached cottage (now a house) which was greatly extended and modernised in 1984. The existing heating system was an oil boiler which was replaced by an external Worster/Bosh Dainsmore 25 boiler with new Joule insulated 200ltr unvented hot water tank, In 2017. This is a 3 pipe pressurised system for the heating and hot water using 22mm pipework for the main feeds and 15mm pipework to the radiators. The radiator circuit is one circuit controlled by a single solenoid valve with a common variable speed pump for the heating and hot water circuit. The hot water has its own solenoid valve all is controlled by a Nest system. About 70% of the radiators have TRVs. The house has had new double glazing and doors and the heat loss is low as we have 200mm insulation in the roof. I have calculated the heat loss using individual wall U values (something I use to do some years ago as an electrical engineer in my consultancy days). Total heat loss is about 5.7Kw without taking into account the hot water cylinder consumption but I usually heat my water overnight on the cheap rate.

I have had some proposals where its just an arbitrary quote, but I have had one quote where the house was surveyed, and I was quite impressed by the installer but not so the quote due to the lack of technical detail.

The proposal I am considering and where I need some advice is as follows:

The proposal is to install a 10 kw Heat Pump using the R32 Midea mono air-to-water unit. The outdoor unit incorporates the main control board, modulating pump, a 7-litre pressure vessel, and a 3-bar pressure relief valve.

In addition, they have proposed to install a Heat Saviour unit that enables any manufactured heat pump to work with an existing heating circuit. The Heat Saviour unit consists of a 20-litre volumiser, a plate-to-plate heat exchanger, and a 3KW heating element, all designed to sit beneath an unvented cylinder within a standard 600 x 600 mm airing cupboard.

To me this looks like it provides minimal disruption to the existing heating and hot water system but my question relates to the Heat saviour volumizer and plate heat exchanger as I am concerned that this has quite a low volume of Glycol and I presume runs at a high pressure.

Does anyone have any experience with the Heat savour product or a plate heat exchanger  and this type of proposed installation what are the pitfalls if any and will it achieve a SCOP above 4 ? do I need to ensure means of displaying the system delta T and should I be asking for some sort of guarantee. Any advice welcome

Also does anyone know of any other good installers in the Bristol area?

Please let me know if you have any questions or require further clarification.

Has anyone had this issue before, or is able to assist in providing calcs to show the roof is OK?  From what I can find out using AI is the roof of this age is able to support this number of panels, but I probably need more info to get the house sale over the post.

Could it have been done better? Any examples of something better?

I’m looking for real-world advice and cost benchmarks for the new Vaillant Arotherm Plus 7kW (cooling-enabled) system with Jaga Briza fan coils for active cooling, plus some guidance on Sunamp Thermino selection.

Project background

• London end of terraced house, approx. 104 m² after extension (2 storey house)
• Nearly EnerPHit-level retrofit following Passive House principles (high-performance fabric, airtightness, MVHR, etc.)
• Zehnder MVHR being installed
• Solar PV + Tesla Powerwall 3 also going in
• Ground floor cooling demand estimated at ~6.6 kW (further reduced with external awning)
• Bedrooms have low loads

Proposed system

• Vaillant Arotherm Plus 7kW (new V2, cooling enabled)
• Heating via underfloor heating (UFH)
• Cooling via Jaga Briza fan coil units
• Hot water via Sunamp Thermino

Jaga Briza concealed units planned: – Living/dining/kitchen: Briza 22 (190 cm) – Study: Briza 12 – Two bedrooms: Briza 22 (75 cm each)

• 100 L buffer vessel
• Sunamp Thermino (undecided between xPlus and ePlus – see question below)
• Heatmiser fan-coil controls
• Units to be installed in ceiling / loft voids where possible

We’ve been quoted roughly £13,800 for the four Jaga Briza units supply + install (including controls). Separately we’ve obtained a direct quote from Jaga for the equipment itself at around £6,000–£6,300 (ex VAT + carriage).

Heat pump (100L buffer) + Sunamp (210L) £17,340 

Total cost of £31,140

Minus the BUS (£7,500): £23,640 

The overall package (ASHP + Sunamp + cooling) is coming in significantly higher than expected once cooling was added. We’re trying to understand whether the installation element for the ASHP and the Briza units is realistic for a London retrofit with ceiling/loft installation and full system integration.

Questions

I feel like I should get a 200L buffer for the ASHP instead of 100L and the 300L thermino instead of the 210L.

1. Has anyone here installed Jaga Briza (or similar) fan coils for cooling with a Vaillant (or other) ASHP? How did they perform in practice — noise, response time, comfort, condensation management?
2. What kind of installed cost (supply + labour) did you see for a similar number of concealed Briza units in a retrofit?
3. Any feedback on the overall cost of adding active hydronic cooling to a Vaillant Arotherm Plus system?
4. Sunamp Thermino choice: We will be pairing the ASHP with a Sunamp Thermino and also have solar PV + Tesla Powerwall. Should we go for the xPlus (heat-pump optimised) or the ePlus (more PV/off-peak focused)? Any real-world experience with either in a similar setup would be really helpful.
5. Any tips on coordination between the ASHP installer and the fan-coil installation (pipework, drainage, controls, heating/cooling changeover logic)?

We’re keen to keep the system as one coherent package if possible, but want to make sure the pricing and component choices are sensible before we commit.

Any experiences, cost data, or lessons learned would be greatly appreciated. Happy to provide more technical details if useful.

Thanks in advance!

Doing the maths on a zero degree day, our heatloss is actually around 4.5 KW, calculated on the actual energy consumed.

We are looking at getting a multi-split for cooling only, but worried that the suggested units are a bit too big, with a combined output of 8.5KW (2x 2.5 and 1x 3.5).

If it takes 4.5KW to maintain a delta of 21 degrees for heating, wouldn't it take 3KW to maintain a delta of 14 degrees for cooling (35 degrees down to 21 degrees)? Or, am I missing something?

The suggested units would seem to be oversized, and I'm concerned about cycling on all but the very hottest days. "Normal" summer days, we are looking at a cooling delta of 4 or 5 degrees.

Hottest OAT this year has been 33 degrees, but the upstairs room have got up to 35 degrees because of solar gain.

1. The comms cable should be 50 mm from the power cable (mine isn’t, it’s been clipped to the power cable). The install manual says it should. 

2. Is it mandatory (MCS or electrical safety regs) for the power cable to be run inside trunking. Mine has just been clipped and runs on the outside of the brickwork. The reason I ask is that the install manual states it should be run in ducting of suitable IP rating to protect from water and possible shock.

I just had a service from BG and they indicated it was a problem/contrary to install manual. I approached the installer and they said it was not an issue.

Thanks

Is there any Haier super aqua gt users on here that could help me connect my unit to the Haier hOn app.

Thanks Glenn