This evening I’ve been doing some max output testing with this Vaillant 5kW ASHP . At 0C outside with 45C flow Vaillant claim an output of 6.6kW is possible: [Screenshot-2024-11-21-00-21-03-11-21-2024_12_21_AM] However, in real world taking into account defrosts it only managed to output 5.3kW, w…

Here’s a summary of the maximum output testing, feel free to add your own test results. Make sure to include a Link to the data, so others can verify: Here’s a link to edit the embedded Google Sheet above: Heat Pump Maximum Capacity cold weather testing This Sheet is private …

Definitely take a look at your strainer, ~900l/min is way too low for a 7kW unit.

Hi Guys. My first post here. I thought I would join in with my observations. I have installed over 40 Vaillant units so far and have around 10 of them on OEM. All my OEM units give around 20%-40% lower outputs than Vaillant sizing guidelines and Vaillant sizing tools suggest. I think Vaillant quote…

Oh, and I totally agree with @glyn.hudson - Those units almost never reach over 40c at design, so designing to above 40c with correct heat loss is not an option. It would simply not work. Again, most get heat loss over by some 20-40%, so that is why people get away with higher design temps, as on-si…

Thank you Szymon, great to see you here and thanks for the valuable insight! Do Vaillant themselves use their ‘peak’ output values for sizing recommendations to their installers, rather than the nameplate rated outputs? I’m very interested in your experience of the 7kW units being noisy at full bl…

Have you found that the 10kW units behave better at design conditions? How then is the tradeoff between being able to cope with continuous defrosts, and efficiency when cycling during warmer periods?

Cycling with Vaillant is not an issue and doesn’t seem to affect efficiency. If I were still specifying Vaillant, I would go a size up, 10kW in place of 7kW. I don’t see a point for a 7kW unit - for me it would be 5 or 10 or 12.

Very interesting, thanks. Are you no longer specifying Vaillant units? If so, which units do you prefer now? I have a 7kW Vaillant with a measured actual heat loss of just under 6kW, and it’s been fine during the recent cold snap, down to -4C. Although it looks like the internal flow/return temp se…

The performance tables I’ve seen mention the EN14511:2018 standard. This standard, as far as I understand, defines the exact outdoor test conditions (including humidity) that should be used for tests, and requires that the results include time and energy spent carry out defrosts. So it’s very disi…

My sensors are off as well, pretty normal. You see some people posting with COP of 10, but it’s invariably their sensors off. Your need to get OEM installed :wink:

[image] dfeist: Auto targets 1200 l/h This is not necessarily true, it also depends on what max. rem. head is set to. The lower that setting is, the lower the resulting auto pump speed.

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Vaillant maximum output capacity testing

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