Help with UFH

[aran]

Hi,

 

I have been reading the forum for a few days and looking for some advice.

 

I am installing UFH in a new build along with an ASHP.

 

The UFH will be laid on top a a 175mm floor slab with 150mm insulation underneath this. I am proposing to use a warmup nexxa system with the panels and have received a quote from them for supply or around £3.8k for an area of around 145m2. This includes everything I would need as below.

 

FYI panels to be used as I don’t know a better way to install as it is directly on the floorslab.

 

Looking for advice on the following.

 

• Is this a reasonable quote, what other manufacturers should I look for, warmup came recommended?
• How many zones should I have? Currently have 4 stats spec’d. I have 1 big open plan kitchen/living/dining and 3 other rooms tv/study/lounge outwith this and then the hall/wc and utility. I know for certain the lounge won’t be occupied that often. Should I look to reduce the number, have seen numerous threads people recommending to use just 1 for the floor but don’t want to heat a room that doesn’t need heated?
• Because the Insulation is below the floorslab what are the pros and cons. I know the slab will act as a thermal store but how will the response times be and should the UFH be set to a temp and be on all day?
• Any other advice and tips would be greatly appreciated. 

Edited June 22, 2022 by aran

[JohnMo]

Not clear from your description, but clarity

 

Floor build up is 175mm concrete, 150mm insulation then UFH pipes, I assume.  Screed above this.

 

If so why not just staple to the insulation.  Lay a thin DPM membrane on the insulation and staple pipes to the insulation.  Job done.

 

Not sure of your heat loads for the house, as that not mentioned.  But looking at the practicalities of the house and UFH.  A room can take more than a few hours to get up to temperature with UFH.  If you don't heat it, it will be uncomfortable when you do want it warm.  Heat from other rooms will migrate towards the lounge, as it cooler, but may not be that warm, so you could have an uncomfortable  room, but you energy usage will be similar to heating it anyway.

 

Are you using weather compensation, if so the thermostats become limit stops for temperature instead of temperature controller.  So they can be quite simple low cost units.

 

ASHP minimum flow requirements.  Smallest zone that can call for heat needs to be able to absorb the min flow of water from the heat pump, otherwise a buffer is needed.

 

 

[aran]

7 hours ago, JohnMo said:

Not clear from your description, but clarity

 

Floor build up is 175mm concrete, 150mm insulation then UFH pipes, I assume.  Screed above this.

 

If so why not just staple to the insulation.  Lay a thin DPM membrane on the insulation and staple pipes to the insulation.  Job done.

 

Not sure of your heat loads for the house, as that not mentioned.  But looking at the practicalities of the house and UFH.  A room can take more than a few hours to get up to temperature with UFH.  If you don't heat it, it will be uncomfortable when you do want it warm.  Heat from other rooms will migrate towards the lounge, as it cooler, but may not be that warm, so you could have an uncomfortable  room, but you energy usage will be similar to heating it anyway.

 

Are you using weather compensation, if so the thermostats become limit stops for temperature instead of temperature controller.  So they can be quite simple low cost units.

 

ASHP minimum flow requirements.  Smallest zone that can call for heat needs to be able to absorb the min flow of water from the heat pump, otherwise a buffer is needed.

 

 

 

Thanks for the reply John. The insulation is actually below the floorslab so unable to staple on. This is the difficulty in finding a cost effective solution. 
 

Dont know too much about weather compensation though?

 

How do I work out the minimum flow?

 

 

[JohnMo]

Go on to heatgeek.co.uk, they have a good write up about the advantages etc. of weather compensation.