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Vaillant - Downstairs radiators not getting warm

samiebon1 · 2025-01-22T09:35:50Z

Had a Vaillant 5kW installed last week and upstairs is getting up to temp ok, but all the downstairs radiators are luke warm at best. I've tried balancing but no such luck. They are column rads, but I've got columns upstairs which are getting warm. A couple of thoughts/questions - could this be resolved by topping up the system pressure more (analogue dial says 1.5, digital says 1.2); could I modify the remaining feed head setting (currently 900); or... Something else? Also, my DHW doesn't seem to be getting up to temp. It has a 3 hour period over night to charge and I've set the offset to 15K which I thought would be enough. Any suggestions? Thanks all!

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Air Source Heat Pumps (ASHPs)

Last Post by Judith 2 years ago

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samiebon1

(@samiebon1)

Eminent Member Member

Joined: 3 years ago

Posts: 25

Topic starter 22/01/2025 8:41 pm

@jamespa thanks James! Ive read through the manuals and found the Eco DHW setting on the Heat Pump controller. I've set it to Manual to see if that gives me the energy in tonight charge cycle.

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Judith

(@judith)

Prominent Member Member

Joined: 3 years ago

Posts: 554

22/01/2025 10:18 pm

@samiebon1 our DHW gets to 48C with a heating temp of ~55C within ~ 45mins but it’s not usually empty (residual ~35 in bottom third of tank).

The layout of our house meant that some upstairs radiators had to be virtually off to ensure the flow went on to downstairs or else the bedroom radiator took all the water.

2kW + Growatt & 4kW +Sunnyboy PV on south-facing roof Solar thermal. 9.5kWh Givenergy battery with AC3. MVHR. Vaillant 7kW ASHP (very pleased with SCOP >4) open system operating on WC

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samiebon1

(@samiebon1)

Eminent Member Member

Joined: 3 years ago

Posts: 25

Topic starter 23/01/2025 7:12 am

@judith did you manage to solve heating the downstairs? Or are you upstairs still off? ... Or when you mean 'off' do you mean the lock shields are only just open? 😄

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Judith

(@judith)

Prominent Member Member

Joined: 3 years ago

Posts: 554

23/01/2025 7:50 am

@samiebon1

When adjusting lockshields its worth bearing in mind that some have a tiny range over which the adjustment makes any difference. Sometimes half a turn or less takes it from fully closed to fully open. This makes getting it 'right' quite tricky.

If you want to know more about this view Heat Geek on 'valve authority'.

2kW + Growatt & 4kW +Sunnyboy PV on south-facing roof Solar thermal. 9.5kWh Givenergy battery with AC3. MVHR. Vaillant 7kW ASHP (very pleased with SCOP >4) open system operating on WC

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