Arotherm Plus ASHP parallel heating?

[vlp2024]

Experts,
Can Arotherm plus air to water heat pump work in parallel:  heat up water cylinder (DHW) and UFH same time? forget about efficiency here, just a parallel operation? how to achieve this?
thanks
 

[JohnMo]

Simple answer no. For example UFH and UVC. As the two have different flow paths via a 3 way diverter valve

 

But if you heated a thermal store, it would provide DHW and heating via the same cylinder -  then the answer is yes

Edited October 3, 2023 by JohnMo

[Conor]

No, you normally run in DHW priority. I.e. if you've your heating set to 24x7, it will switch to heat the hot water tank when temp drops below setpoint, then switch back to heating.

[DanDee]

29 minutes ago, vlp2024 said:

Experts,
Can Arotherm plus air to water heat pump work in parallel:  heat up water cylinder (DHW) and UFH same time? forget about efficiency here, just a parallel operation? how to achieve this?
thanks
 

 

I can tell you how to achieve this with any heat pump if:

 

Why do you need this, what is in your mind?

[JoeBano]

I successfully did this by mistake on my heat pump 😂 was wondering why my hot water kept disappearing. 

[sharpener]

2 hours ago, vlp2024 said:

Experts,
Can Arotherm plus air to water heat pump work in parallel:  heat up water cylinder (DHW) and UFH same time? forget about efficiency here, just a parallel operation? how to achieve this?
thanks
 

 

You would need to replace the 3-port valve with two 2-port ones if you want them to be separately controllable, and change the wiring to the VR70 or VR71 wiring centre to suit. Perhaps setting the DHW as a dummy heating zone would be easier if you do not need features like anti-legionella. What does your installer say?

 

Don't know though if Vaillant would support this, IIRC it is not on any of the standard Arotherm plus schematics. I am thinking of doing this for reasons connected with not changing my current inaccessible hw cylinder, and they are coming for a site vist so I should be able to tell you the outcome in a fortnight's time(!)

[JamesPa]

6 hours ago, vlp2024 said:

Experts,
Can Arotherm plus air to water heat pump work in parallel:  heat up water cylinder (DHW) and UFH same time? forget about efficiency here, just a parallel operation? how to achieve this?
thanks
 

On the basis that both are just heat sinks, with the correct plumbing then yes in principle but:

 

You will be dividing the total output between the two so both may struggle 

 

The efficiency for space heating will be awful because it's running at a much higher ft than necessary 

 

Not sure why you would want to do this, perhaps if you told us we could collectively suggest a solution to whatever problem you are trying to solve.

[JamesPa]

5 minutes ago, JamesPa said:

On the basis that both are just heat sinks, with the correct plumbing then yes in principle but:

 

You will be dividing the total output between the two so both may struggle 

 

The efficiency for space heating will be awful because it's running at a much higher ft than necessary 

 

Not sure why you would want to do this, prima facie it's rather a perverse way to operate either a heat pump or a gas boiler with weather compensation or equally a gas boiler operating at a lowish flow temperature for best condensing.  Perhaps if you told us we could collectively suggest a solution to whatever problem you are trying to solve.

 

[sharpener]

Vaillant ppl told me two weeks ago that they want to see HW priority and do not support S-plan setups like this. Nevertheless I am hoping to fit a mid-position valve rather than a plain diverter so that by a simple wiring change it will be possible to experiment with heating the DHW and charging the thermal store at the same time, see this thread. But that is a special instance where both flows are required at the same temp.

[JamesPa]

54 minutes ago, sharpener said:

Vaillant ppl told me two weeks ago that they want to see HW priority and do not support S-plan setups like this. Nevertheless I am hoping to fit a mid-position valve rather than a plain diverter so that by a simple wiring change it will be possible to experiment with heating the DHW and charging the thermal store at the same time, see this thread. But that is a special instance where both flows are required at the same temp.

Whatever happens next, even if you need to play some more tricks to be satisfied with the dhw, this is definitely a result.  Well done and good luck with the install.  May there be many more who are not forced to replace their dhw cylinder!