Renovating flat: best heating options?

lb00

Hi all,

We’ve just bought a flat in London and are about to start renovating it. The flat is on the 13th floor of a 22-storey building, roughly 75 sqm in size. The building was previously used as offices and was fully converted into residential flats in 2002.

There’s no gas supply, and hot water is provided through a Megaflo system. Currently, the flat has two old electric heaters. There’s also an existing air conditioning system, with an external unit on the balcony and air vents in the lounge and the two main bedrooms. I think the previous tenants were just using space heaters.

Here are the pics: https://postimg.cc/gallery/4KK2KCZ

I’m considering a few different options and would love some advice:

1. Night storage heaters on an Economy 7 tariff.

2. Replacing the air conditioning unit with an air source heat pump and installing wet underfloor heating (would require freeholder consent, so not sure how feasible this would be).

3. Replacing the air conditioning unit and using the existing air vents for heating (feasible for freeholder).

4. Electric underfloor heating.

Since I plan to install tiles throughout the flat, UFH seems appealing, as I’ve heard that tiles have good thermal mass and can distribute heat effectively. However, we need to keep the flat warm throughout the day, not just in the mornings and evenings, which makes efficient (and not crazy expensive) heating a priority.

What are your thoughts on these options? Any suggestions or experiences would be greatly appreciated!

Thanks in advance!

Alderbank

Will you live there or rent it out?

What's the insulation like? Many office buildings had little or none.

What's the orientation? Big difference in daytime between north-facing and south-facing.

Reed_Richards

A modern air conditioning unit is an air-to-air heat pump and can be used for both heating and cooling.  It should be very efficient, more so than an air-to-water heat pump.

Newbie_John

Quite depends how long you're planning to live there..

Cheapest short term would be something like Phillips ceramic heater <£100.

Most efficient replacing air con into a heating one as well as improving insulation in the house. Probably will pay itself off in 5+ years.

Gerry1

Don't even think of electric underfloor heating !  Apart the running costs bankrupting you, it'll seriously devalue your flat if/when you want to sell; any prospective buyers will drop out when they find out. 👎

HHR NSHs such as Dimplex Quantum would be a good solution.

However, the existing air conditioning unit needs further investigation.  Is it working effectively and reliably?  Can it be used for heating?  If so, it may need little more than a service.

However, if can't be re-used in this way, or is almost life expired, then an air-to-air heat pump could be a good solution giving heating and cooling. You wouldn't get the government grant, but nor would you have the costs of installing large wet radiators.  Could be very beneficial if summers get hotter, especially if south facing, and it will be a great selling point.

lb00

@Alderbank

We will live there so are happy to spend a bit more to be comfortable in the winter. My mum and my sister will be staying with us long periods so the flat will have to be heated throughout the day so not only mornings and evenings.

Insulation is okay to be fair.

Orientation is East for all the window openings (balcony in lounge and windows in bedrooms).

@Reed_Richards @Newbie_John @Gerry1

Air con is a Mitsubishi Mr Slim R407C model, installed in 2002. I am attaching some pics. There are air vents in the lounge and two bedrooms.

It already does both heating and cooling. I've tried it and it works.

One issue is my mum really dislikes air heating and would prefer radiators or UFH i.e. heat coming from surfaces rather than air. Reason is we had a Midea cooling/heating system in Italy and it's given us lots of problems at the point we had to put radiators in the end.

I've been quoted £1400 for each of the Dimplex Quantum fitted - is it reasonable?

Many thanks!

Gerry1

Sounds about right but depends on the details.  What sizes are the Quantums, and do they have all the (probably unnecessary) bells and whistles?  If in doubt go for the larger size otherwise they may not have enough oomph to last a full day when there's a Beast From The East.  How many quotations did you get?

Does it include cabling to give each heater a 24/7 supply and an E7 supply?  Make sure you're always comparing like with like.  Will the cables be chased into the wall or run on the surface?  Make sure you know exactly what is included and what is not.

Make sure at least one E7 outlet has a neon indicator, especially if you go for the 'bodge' of single supply operation.  Best avoided, especially in locations where there's no existing spur for a panel heater.

lb00

Gerry1 said:

Sounds about right but depends on the details.  What sizes are the Quantums, and do they have all the (probably unnecessary) bells and whistles?  If in doubt go for the larger size otherwise they may not have enough oomph to last a full day when there's a Beast From The East.  How many quotations did you get?

Does it include cabling to give each heater a 24/7 supply and an E7 supply?  Make sure you're always comparing like with like.  Will the cables be chased into the wall or run on the surface?  Make sure you know exactly what is included and what is not.

Make sure at least one E7 outlet has a neon indicator, especially if you go for the 'bodge' of single supply operation.  Best avoided, especially in locations where there's no existing spur for a panel heater.

The quote I've been given is very open ended - I will chase the electrician to make sure they account for all of this. I will get some other quotes from Dimplex installers close to me. Or would you recommend buying the heaters somewhere online together with the Dimplex Hub and then just asking the electrician to quote the fitting?

Also just to double check: I understand the dimplex quantums emit most heat through convection and a bit through radiant heat from the bricks. So do you get the feel of hot air being pumped in the room from the heaters?

Thanks!

Gerry1

Probably no hard and fast rules here, I suspect it's more important to get experienced people who are knowledgeable and diligent rather than saving the odd pound or two.

You'll remember any aggro or botched work long after the price has been forgotten.  Talk to a few and find one with whom you're comfortable.

Also, if the installer sells Dimplex but you've bought elsewhere he may not be best pleased, a bit like a bookshop owner if you browsed and found a good book but then said you'd be getting it cheaper from Amazon.  😱

My experience of NSHs was the old style box of bricks many moons ago, but my understanding is that the high insulation means there's no radiant heat and the case stays cool.  Warm air is blown out when needed from the bottom.

Are you really sure you need the Hub and the remote control facilities?

Scot_39

Not sure the current British Gas special is truly variable time of use - but it does iirc need the hub.

Previous trials - possibly true variable time of use ? - were offered by Ovo and then EDF - maybe 4-5 years ago - using something called Kaluza (sp ??) to control the charging times iirc - I have vague recollection the hub acted as the internet gateway.

Scot_39

lb00 said:

Gerry1 said:

Sounds about right but depends on the details.  What sizes are the Quantums, and do they have all the (probably unnecessary) bells and whistles?  If in doubt go for the larger size otherwise they may not have enough oomph to last a full day when there's a Beast From The East.  How many quotations did you get?

Does it include cabling to give each heater a 24/7 supply and an E7 supply?  Make sure you're always comparing like with like.  Will the cables be chased into the wall or run on the surface?  Make sure you know exactly what is included and what is not.

Make sure at least one E7 outlet has a neon indicator, especially if you go for the 'bodge' of single supply operation.  Best avoided, especially in locations where there's no existing spur for a panel heater.

The quote I've been given is very open ended - I will chase the electrician to make sure they account for all of this. I will get some other quotes from Dimplex installers close to me. Or would you recommend buying the heaters somewhere online together with the Dimplex Hub and then just asking the electrician to quote the fitting?

Also just to double check: I understand the dimplex quantums emit most heat through convection and a bit through radiant heat from the bricks. So do you get the feel of hot air being pumped in the room from the heaters?

Thanks!

Depends what you mean by pumped out.

An actual user will no doubt be along to rubbish this view - but the fans in the Quantums are iirc about 11W - and I am not sure but if thats blowing across a full width on the larger units vents - I suspect not that powerful. 

But having said that some radiator top boost devices are similarly rated and get good reviews.

.

[By comparison a 12" desk fan might use 30-40W - and my 16" floor fan use to cool in summer - a far larger 45-70W (just tried it on low / high looking on IHD).]

11W is about the same power as two mini usb fans.  I suspect more than a metre away - you wont really feel any forced air / draft effect at all - and they blow out at the bottom of the units - so at ankle type level.  

However size for size - it is enough air flow over passsive convection devices - to potentially significantly up available peak power output (that just by comparison of modern specs for size - againt my old passsive - not scientific - just IMO. )

IIRC Dimplex quote a peak of c1.5kW output heat for the 150 with a 3.3. kW input.

My similar full sized passive convection / radiation old NSH - more like 1.1 kW max iirc - with a larger 3.6kW charge rating.