Plumber wants to put in 2 huge radiators to each bedroom

[CalvinHobbes]

Our ceilings are ridiculously high but the plumber says because we are going with an ashp we need 2 tall radiators on each bedroom but I think it will look horrible. The house will be near passive. In the rented house I am in, which leaks like a sieve, we never use the radiators upstairs. I think we switched them on twice in 3 years. So why am I putting them in upstairs? We have nearly 12kw of solar panels on the roof. Could we not just use an electric heater if it needs a boost?

[Iceverge]

Never mind passive, you won't need rads in rooms upstairs in any house with just minimal insulation in my opinion. 

 

A slight caveat to this is the more area that you can dissipate heat through from the heat pump will allow you to run it at lower flow temp and achieve a better COP. 

 

 

 

[CalvinHobbes]

Thanks, it's about 180m2 , ceilings about 3m downstairs and it's underfloor heating. 

So if we don't put in radiators upstairs surely we need a smaller heat pump? 

[Conor]

Why aren't you putting UFH upstairs?

 

Any yes, 12kW is way too big. You'd get away with a 5kW. 

 

The pH standard requirement of 10W/m² heating remittance means (if you meet the standard) is a max heating output of 1.8kW. of course, you want a good buffer for this to account for suboptimal COP, and for faster hot water, so a 5kW would be perfect.

Edited July 28 by Conor

[MikeSharp01]

3 hours ago, CalvinHobbes said:

Thanks, it's about 180m2 , ceilings about 3m downstairs and it's underfloor heating. 

So if we don't put in radiators upstairs surely we need a smaller heat pump? 

If its a well insulated slab and a large area then you have enough output area for the whole house, if you do the sums, 180m² slab, with UFH gives you 180m² of heat output to warm the house. We have tall vertical multi hollow pipe rads here, they are good for output area but if you have a 10 pipe version of these 3m tall (ours are 2m) you only have about 5m² of heat output or approx 3% of the slab area per rad. Ask your plumber to install towel rads in the bath rooms so they can keep the towels cosy and that should be enough. With that much PV you can retro fit some electric heaters but you won't need to. 

 

 

Edited July 28 by MikeSharp01
typo

[nod]

4 hours ago, Iceverge said:

Never mind passive, you won't need rads in rooms upstairs in any house with just minimal insulation in my opinion. 

 

A slight caveat to this is the more area that you can dissipate heat through from the heat pump will allow you to run it at lower flow temp and achieve a better COP. 

 

 

 

Plus 1 

We never used our tiny Rads  in six years 

[JohnMo]

4 hours ago, CalvinHobbes said:

 

So if we don't put in radiators upstairs surely we need a smaller heat pump

No, your house heat loss is what it looses. If you just have UFH and no radiators it still looses the same amount of heat energy. Radiators everywhere and no UFH it still looses the same heat energy.

 

Put in provision for electric panel heaters in bedrooms.

 

At 180m² house and well insulated, your heat loss isn't going to be much more than 3kW, so you should be on the smallest heat pump anyway, any bigger than 6kW, welcome to big bills from short cycling.

 

[Dave Jones]

stop!

 

Use fancoils in the bedrooms, they are much smaller footprint as they have a heat exchanger in them. Biggest plus as they are close to air-con in the summer when you turn your heat pump into cooling mode.

[JohnMo]

Just now, Dave Jones said:

stop!

 

Use fancoils in the bedrooms, they are much smaller footprint as they have a heat exchanger in them. Biggest plus as they are close to air-con in the summer when you turn your heat pump into cooling mode.

That is the best advise. They will take the same flow temp as your UFH, so no mixers are needed. Run everything from the ASHP circulation pump, all as a single zone, no room thermostats needed.

[Dave Jones]

one of the best decisions we made on our build. Was a roll of dice as couldn't find any 'official' advice on using fancoils for cooling. They consume virtually no power as its the fan is a small pc type one, keeping our bedrooms at 20/21 with a 15/16c flow temp with outside temps 30c.

 

If you do go down this route make sure the flow and return is insulated everywhere, inside stud etc as it will get condensation on it if you want air con levels of cooling.

[ProDave]

I am one of many on here, building a low energy well insulated and air tight house that chose NOT to put any heating in the bedrooms.  I did put cables in for electric panel heater points in the bedrooms, but they have never been needed.  We get enough heat from downstairs to keep the bedrooms comfortable without any extra heating in them.

[LaChab]

 

Morning, That sounds really interesting.  @Dave Jones Could you post a link to the fancoils you fitted.......

And where (floor, ceiling..) did you fit them?

[joe90]

9 hours ago, CalvinHobbes said:

because we are going with an ashp we need 2 tall radiators on each bedroom

 

3 hours ago, nod said:

We never used our tiny Rads  in six years 

 

9 hours ago, CalvinHobbes said:

In the rented house I am in, which leaks like a sieve, we never use the radiators upstairs.

So why I a better insulated house do you think you need radiators in the bedrooms?

2 hours ago, ProDave said:

I did put cables in for electric panel heater points in the bedrooms, but they have never been needed. 

With my build (near passive)I had no heating in bedrooms. No extra cables fir panel heaters but sockets in position for electric heaters if required (never used).

[nod]

We’ve spent 5k on tall stainless Rads for the upstairs simply because they look nice and possible resale I’m pretty sure we won’t ever use them 

[joe90]

2 minutes ago, nod said:

possible resale

Yes, Because most people don’t realise they are not needed (good plan).

[CalvinHobbes]

Huge thank you. 

[G and J]

1 hour ago, LaChab said:

 

Morning, That sounds really interesting.  @Dave Jones Could you post a link to the fancoils you fitted.......

And where (floor, ceiling..) did you fit them?

And can you hear them when they are running?

[JohnMo]

54 minutes ago, G and J said:

And can you hear them when they are?

They are pretty quiet, and WAY better than trying to sleep in a hot bedroom. My wife has one in her massage room where she likes silence, and doesn't seem to bother her. We have a Myson iVector. 

 

Winter you most likelihood will not need them. In use during summer the cool should fall to the ground floor, aiding the UFH which is also in cooling mode.

[saveasteading]

I think all plumbers say to put rads upstairs. It is what plumbers know and do.

Hence the expectations of most occupiers and future buyers are probably the same.

 

I'm thinking of short runs of aluminium skirting with ufh pipes in them. Perhaps we need some visual link to confirm they are actually radiators. A control knob adjacent, whether connected or not? Coloured red? Sign saying 'warning: skirting may  be hot!' 

 

Otherwise a quote from @ProDavesaying ' don't be a wimp, it is warm enough with the heat from downstairs and 18° is plenty'.

[Dave Jones]

7 hours ago, LaChab said:

 

Morning, That sounds really interesting.  @Dave Jones Could you post a link to the fancoils you fitted.......

And where (floor, ceiling..) did you fit them?

 

 

https://www.bpcventilation.com/panasonic-fan-coil-unit

 

 

[CalvinHobbes]

jeekers the fan coil units are a bit pricey!

[G and J]

18 hours ago, JohnMo said:

They are pretty quiet, and WAY better than trying to sleep in a hot bedroom. My wife has one in her massage room where she likes silence, and doesn't seem to bother her. We have a Myson iVector. 

 

Winter you most likelihood will not need them. In use during summer the cool should fall to the ground floor, aiding the UFH which is also in cooling mode.

Getting a bit confuddled here.  If your ASHP is in cooling mode do you somehow disable the summer bypass so that the air you’ve spent electricary cooling isn’t promptly ejected?  I think the MVHR will cool the incoming air if the heat exchanger is engaged and the extract air is cooler than the intake air.

[JohnMo]

6 minutes ago, G and J said:

Getting a bit confuddled here.  If your ASHP is in cooling mode do you somehow disable the summer bypass so that the air you’ve spent electricary cooling isn’t promptly ejected?  I think the MVHR will cool the incoming air if the heat exchanger is engaged and the extract air is cooler than the intake air.

MVHR summer bypass works in hot periods when outside air is cooler than the air being rejected. Therefore bypassing the heat exchanger.  If the house is cooler than outside it should operate in normal mode. So cool the incoming air via the heat exchanger.

[Dave Jones]

11 hours ago, CalvinHobbes said:

jeekers the fan coil units are a bit pricey!

 

its all relative. wouldnt put them in a council house or a legoland estate house but a nice self build ?

[Dave Jones]

23 minutes ago, G and J said:

Getting a bit confuddled here.  If your ASHP is in cooling mode do you somehow disable the summer bypass so that the air you’ve spent electricary cooling isn’t promptly ejected?  I think the MVHR will cool the incoming air if the heat exchanger is engaged and the extract air is cooler than the intake air.

 

forget about MVHR for cooling there is nowhere near enough air flow. Think of your air con working via trickle vents.

 

we have the zehnder cooling/heating battery ont he mvhr intake(£2k) and it makes no noticeable difference to cooling. We had it purely for winter use. Wouldn't bother again though.