Air source heat pump and UFH

PDS · Oct 6, 2019

Hi Guys,
I’ve been asked to fit an air source heat pump with unvented hot water tank, and UFH on downstairs concrete slab and spreader plates upstairs.
Has anyone fitted this before and taken pictures so I can see a neat or workable layout please?
Look forward to hearing from you.

Sharp Point · Oct 6, 2019

Me personally would chose a brand that would suit the job for size, practicality and cost. Then ask their tech dept for a design and control usage. Have you considered how to top up the hot wAter temp to kill off legionnaires? As I don’t think that there’s a HP out there yet, that can get to 65/70 degrees.... I maybe wrong, I haven’t kept up with the technology like I use to.

Brambles · Oct 6, 2019

Which air source heat pump are you proposing, the Panasonic range?

Are you proposing to lay the ground floor ufh onto an existing slab, if so do you know what level of insulation is beneath the slab, to calculate the level of insulation required.

Personally, I don’t like (aluminium) spreader plates if they are to be retrofitted into an existing property. They are ok for new build. For retrofitting I find that biscuit mix gives a good even distribution of heat.

If you go down the aluminium spreader plate route, warn the customer that the plates will adversely affect wifi and mobile phone signal reception.

I append two photos, one of the floor ready for screeding and the second of the plant room - albeit the pump here is ground source. For air source with a split unit the plant room would be identical.

Hope this helps

PDS · Oct 6, 2019

Brambles said:
Which air source heat pump are you proposing, the Panasonic range?

Are you proposing to lay the ground floor ufh onto an existing slab, if so do you know what level of insulation is beneath the slab, to calculate the level of insulation required.

Personally, I don’t like spreader plates if they are to be retrofitted into an existing property.

I append two photos, one of the floor ready for screeding and the second of the plant room - albeit the pump here is ground source. For air source with a split unit the plant room would be identical.

Hope this helps

Hi Brambles,
The downstairs will be on a slab and I plan on using 100 mm insulation with a vapour barrier.
For the upstairs, the customer wanted to use standard rads, that were going to be massive. Aluminium rads too expensive. Therefore, I suggested spreader plates between the joists with wooden floor fitted above.
I was going to use the Mitsubishi heat pump.
[automerge]1570380553[/automerge]
Thanks for the images, very helpful.

Brambles · Oct 6, 2019

That should be fine. If you have the option tongue and groove flooring upstairs seems to give a better level of heat than chipboard (but there is a price to pay).

Bear in mind, with the MHI (Mitsubishi) pumps they can only really be used with Mitsubishi controls. Panasonic - the domestic range - can be used with any conventional (Honeywell) control system and are modular if you want to add solar at a later date.

Hope this helps
[automerge]1570381181[/automerge]
A final point - not teaching you to suck eggs - I always take customers for air source heat pumps to see an existing installation.

Most have no idea as to how much noise the external evaporator units make. It may seem tedious - but I have had a number of customers who were wedded to the idea of air source until they heard the noise and in one case realised the size of plant room required.

PDS · Oct 6, 2019

Brambles said:
That should be fine. If you have the option tongue and groove flooring upstairs seems to give a better level of heat than chipboard (but there is a price to pay).

Bear in mind, with the MHI (Mitsubishi) pumps they can only really be used with Mitsubishi controls. Panasonic - the domestic range - can be used with any conventional (Honeywell) control system and are modular if you want to add solar at a later date.

Hope this helps
[automerge]1570381181[/automerge]
A final point - not teaching you to suck eggs - I always take customers for air source heat pumps to see an existing installation.

Most have no idea as to how much noise the external evaporator units make. It may seem tedious - but I have had a number of customers who were wedded to the idea of air source until they heard the noise and in one case realised the size of plant room required.

Thanks for that. I didn’t take into account the controllability of the system and am pleased you brought that to my attention.

ShaunCorbs · Oct 6, 2019

@quality your sort of subject

quality · Oct 7, 2019

I will add the Mitsubishi FCT controller albiet quite complex is very good

snowhead · Oct 7, 2019

Brambles said:
Most have no idea as to how much noise the external evaporator units make. It may seem tedious - but I have had a number of customers who were wedded to the idea of air source until they heard the noise and in one case realised the size of plant room required.

Also not forgetting to take account of the effect of the noise on neighbours.
Sound travels a long way and is even more noticeable with variable speed fans.

Air source heat pump and UFH

PDS

Sharp Point

Brambles

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