Does legionella cycle also heats up radiators?
Hello. Beginner's question:
I have a system with a ASHP and a hot water tank.
When the legionella cycle (Friday 1pm for 1 hour) kicks in my radiators also heat up. Is this supposed to happen?
I am suspecting the valve that controls where the hot water from the pump goes (diverting to DHW or Heating) is not working well, and DHW is leaking to the radiators.
Welcome to the forums @bbmorales
No, that shouldn’t be happening. It sounds like you’re on the right track with your diagnosis though. During the legionella cycle, only your hot water tank should be heating up, not the radiators. This suggests that the diverter valve may be faulty and allowing hot water to flow into the heating circuit. A photo of the diverter valve would be helpful.
The other question this poses is that I assume your heating is off at the moment and you’re only using your heat pump for hot water production. So why is your system coming on at all and distributing heat to your rads. Does your circulation pump come on when the legionella cycles starts?
Buy Bodge Buster – Homeowner Air Source Heat Pump Installation Guide: https://amzn.to/3NVndlU
From Zero to Heat Pump Hero: https://amzn.to/4bWkPFb
Follow our sustainability journey at My Home Farm: https://myhomefarm.co.uk
Hi @editor Mars, many thanks.
Regarding the images, I've uploaded two, hopefully this gives you an idea of the system.
Regarding your other question
"Does your circulation pump come on when the legionella cycles starts? "
Apologies for the question, but where is this pump and how to I verify this?
I have not disabled completely the heating, but I can try doing so next Friday (disable completely the heating, leaving on only DHW).
Thanks for your help!
@bbmorales let's backtrack a little bit. Can you please share more information about the system you have (brand and model of heat pump would be a good starting point)? We'll need to ascertain whether your heating is in fact off.
Buy Bodge Buster – Homeowner Air Source Heat Pump Installation Guide: https://amzn.to/3NVndlU
From Zero to Heat Pump Hero: https://amzn.to/4bWkPFb
Follow our sustainability journey at My Home Farm: https://myhomefarm.co.uk
There is no need, imo, to run a legionella cycle as often and it would be better run during the night on cheaper rate electricity. The ASHP heats to 50c and the immersion takes over to 60c. Expensive on day time rate on a weekly basis. Needn’t be for as long as an hour either so far as I know.
Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
Faulty 3 port diverter….
Easiest fix is to disable the legionella program.
Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.
My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.
@bbmorales it's a personal preference and depends on the likelihood of bacteria proliferating in your tank. We run a Legionella cycle every two weeks. Since we work from home and use hot water frequently, the water in our cylinder is constantly being drained and replaced, preventing stagnation. This routine works for us. However, some homeowners choose to turn it off completely.
Buy Bodge Buster – Homeowner Air Source Heat Pump Installation Guide: https://amzn.to/3NVndlU
From Zero to Heat Pump Hero: https://amzn.to/4bWkPFb
Follow our sustainability journey at My Home Farm: https://myhomefarm.co.uk
- 25 Forums
- 1,479 Topics
- 30.8 K Posts
- 26 Online
- 1,257 Members
Join Us!
Latest Posts
-
RE: Delivering a smart and secure electricity system: government consultation
I wonder how many of us actually submitted a response t...
By Transparent , 2 hours ago
-
RE: Two possible heat pump routes - how to evaluate them?
@lucia The heat geek cheatsheet on the article only ...
By bontwoody , 20 hours ago
-
RE: Do you think that installing an air source heat pump has increased the value of your property?
I agree with everything you've said, @toodles, and you'...
By Majordennisbloodnok , 1 day ago
-
RE: Looking for Battery Storage Advice
This house has a full height cellar, so no issues with ...
By FlyingScot , 1 day ago
-
RE: My horrific Samsung heat pump installation and experience
@iantelescope Your system differs from most in that y...
By Derek M , 2 days ago
-
RE: SCOP and seasonal variations
@judith Its a good argument for separating the heating ...
By bontwoody , 3 days ago
-
RE: New Fogstar 15.5kWh upright solution
I think that question should be relocated in a Topic ab...
By Transparent , 3 days ago
-
RE: Getting the best out of a heat pump - is Homely a possible answer?
@potatoman Yes, we have a Homely smart controller attac...
By Toodles , 3 days ago
-
RE: Basic advice/opinions on complex heating system: Chromagen
Thanks, Derek, that gives me a lot to think about. I'll...
By PeterM , 3 days ago
-
RE: Legionnaires' Disease & Home Hot Water: Understanding Risks and Prevention
Let's note that the Equinox Trial is being run by compe...
By Transparent , 4 days ago
-
RE: Would I be unkind to the Grid?
@judith Oh Judith! I feel for you, during Covid Lockdow...
By Toodles , 5 days ago
-
RE: Heat Pump Books For Homeowners – Bodge Buster & From Zero To Heat Pump Hero
Following on from the success of Bodge Buster, we're ve...
By Mars , 6 days ago
-
Oh I didn't see that - so I'm getting 300-320 ohms on t...
By spacebiscuit , 6 days ago
-
RE: Do you know the lifespan of your heat pump?
The figure I've seen claimed is usually 20 years.
By IvanOpinion , 6 days ago
-
RE: Samsung gen 6 - how to manually turn on/off immersion (booster)
@ecobaker absolutely correct - I'd only manually kick i...
By Old_Scientist , 7 days ago
-
I understand the risk, but unless you compel all heat p...
By JamesPa , 7 days ago
-
RE: Air source heat pump roll call
Ah... the proximity of LCT installations is not somethi...
By Transparent , 7 days ago
-
An interesting experiment on LLHs.
By IvanOpinion , 7 days ago
-
-
RE: Confusion over Octopus Tariffs
I attended a National Grid Community Energy workshop la...
By Transparent , 1 week ago
Latest Topics
-
Looking for Battery Storage Advice
By FlyingScot 3 days ago
-
Would I be unkind to the Grid?
By Toodles 7 days ago
-
Do you know the lifespan of your heat pump?
By Mars 1 week ago
-
Renewable Heating Hub Award Nominations
By Mars 2 weeks ago