Search with Wattson

Notifications

Clear all

Joining the Renewable Heating Hub forums is completely free and only takes a minute. By registering you’ll be able to ask questions, join discussions, follow topics you’re interested in, bookmark useful threads and receive notifications when someone replies. Non-registered members also do not have access to our AI features. When choosing your username, please note that it cannot be changed later, so we recommend avoiding brand or product names. Before registering, please take a moment to read the Forum Rules & Terms of Use so we can keep the community helpful, respectful and informative for everyone. Thanks for joining!

[Solved] Vaillant aroTherm not heating with many faults

Anon67 · 2026-01-10T21:01:29Z

I have a 3 year old 10kW vaillant aroTherm heat pump connected to dhw and ufh. The heat pump kicks in on demand for hot water but when it comes to heating it faults, getting a mixture of faults F.732 Compressor outlet temperature too high F. 733 Evaporation temperature too low F. 0521 Outdoor temperature sensor signal invalid Does anyone have any ideas how I can get the heating back on even temporary? Until I can get someone to look at it on Monday. I tried looking through the menu but there doesn't seem to be any option to force heat.

Page 2 / 2 Prev

Air Source Heat Pumps (ASHPs)

Last Post by Majordennisbloodnok 5 months ago

16 Posts

5 Users

14 Reactions

2,721 Views

RSS

Anon67

(@anon67)

Active Member Member

Joined: 5 months ago

Posts: 6

Topic starter 16/01/2026 11:59 am

Thank you all for your help with trying to get this sorted. Just a quick update to close this thread off incase anyone has similar in the future.

I phoned Vaillant on Monday, spoke to the tech support line, he said going off the fault codes he suspected it to be low on refrigerant so he booked me an engineer visit.

Tuesday morning the DHW started faulting displaying similar messages compressor blocked etc

Guy came out late yesterday afternoon, zero pressure in the refrigerant circuit, pressured it up with his test gas, could watch pressure dropping off immediately and could physically hear a leak. Traced to the evaporator, which isn't replaceable or repairable so they are replacing the full unit.

Hopefully it'll be all sorted by next week.

This post was modified 5 months ago by Anon67

👍

ReplyQuote

ASHP-BOBBA

(@ashp-bobba)

Prominent Member Member Professional+

Joined: 2 years ago

Posts: 478

16/01/2026 12:04 pm

@anon67 Pleased they are replacing it for you and I am pleased when I said they are quite good with their warranty they actioned it.

Good luck with the replacement

AAC Group Ltd covering the Kent Area for design, supply and installation of ASHP systems, service and maintenance, diagnostics and repairs.

👍

ReplyQuote

Mars

(@editor)

Illustrious Member Admin

Joined: 5 years ago

Posts: 4709

16/01/2026 11:24 pm

@anon67, glad to hear they’ve found the issue and that it’ll be replaced. Hopefully that goes smoothly. Will Vaillant be doing the replacing themselves?

Get a copy of The Ultimate Guide to Heat Pumps

Subscribe and follow our YouTube channel!

ReplyQuote

Majordennisbloodnok

(@majordennisbloodnok)

Famed Member Moderator

Joined: 4 years ago

Posts: 1891

17/01/2026 1:05 pm

The mark of a good company to deal with is less to do with them not having issues as much as how they deal with them when they arise. Glad you’re on the way to a quick resolution and props to Vaillant so far for playing fair.

105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and SPH5000 inverter
1 x Myenergi Zappi
1 x VW ID3
Raised beds for home-grown veg and chickens for eggs

"Semper in excretia; sumus solum profundum variat"

👍

ReplyQuote