Space Heating Options

[Gill]

As I posted in another thread, I've been trying to understand the options I should be considering for space heating and DHW.  We have a few small layout changes planned along with refurb our bathroom and shower room so deciding on heating and DHW system seems like the sensible first stage.

Would appreciate any input into pros / cons of the various systems I'm thinking about and also any systems that I haven't listed that I should be thinking about.   

 

• Limitations: No Gas supply
• Property : Two bed bungalow single storey  (decline and die home)
• Current system : Storage heating (not high heat retention).  Electric heaters used for top up. DHW through an immersion tank.
• Heat Loss : I've had a stab at completing the spreadsheet making assumptions about u values of windows, doors and Air Changes.  The monthly figures are eyewatering.  The highest actual daily usage we've hit in one day was 96kWh (which included DHW ).  This was December when the temps between -3 and -9 consistently.  That said, we don't maintain 18 degrees across the whole house.  The hall and kitchen have no heating, the shower room has a towel rail we never use, the main bedroom only gets a blast of heat in the exceptionally cold weather.  The second bedroom gets the storage heater overnight if WFH the following day.  
• Improvements : I've not factored in up coming improvements on the spreadsheet.  All windows will be replaced in the next month that should give approx U value of 1.1.  Following on from that, we'll get the cavity walls insulated.  
• I also plan to put in a MHRV system (in our cold roof).  Have read mixed thoughts on this but I think i'm sold on the broader benefits of MHRV even homes that cannot achieve great airtightness.
• Solar seems like a no-brianer - we've got reasonable sized unobstructed south facing roof space and also a smaller south facing garage roof 

 

Some of my thinking so far....

 

Stick with Storage Heaters

Pros

• No plumbing required - Minimal disruption.  
• Economic with ECO 7 tariff
• Will perform better when we insulate 

Cons: 

• Delivers heat when we dont need it.  The house is empty daytime twice a week at least.
• May still require top up heating (at peak rate)
• High Heat Retention models don't come cheap and aside from user reviews on manufacturers web sites, haven't seen real world feedback from anyone that's upgraded to HHR.  
• Bulky / Consuming wall space 
• Require a separate solution for DHW

 

ASHP & Oversized Rads
Pros

• Heat when we want it
• Plenty info on how to size things correct and tweak for performance
• Can supply DHW

Cons 

• Disruption of installing a wet heating system 
• Oversized Rads consuming wall space
• Don't see this working with with ECO 7 tarrif

 

ASHP & Underfloor Heating
Pros

• No radiators
• No cold patch at floor level
• Can supply hot water

 

Cons 

• Most Costly Option
• Requires wet heating system 
• Efficiency concerns with suspended flooring
• Potential need to build up the flooring throughout the house
• Don't see this working with with ECO 7 tariff

 

A2A 
Pros

• Cooling  & Heating.  Cooling would work well with solar.
• Placement frees up wall space 

Cons: 

• No where near as much info available on A2A as ASHP so hard to get a good understanding of pros / cons / suitability
• Would MHRV system play nice with A2A?
• Require a separate solution for DHW
• Don't see this working with with ECO 7 tariff

 

Heat loss calculator - Master.xlsx

[SteamyTea]

I shall look at it later, just recovering for my weekly drive up country and back.

 

As you have a suspended floor, it may be easier to insulate than you think.  Can you crawl under it?

[Iceverge]

A couple of A2A @ a COP of 4

 

and an

 

ESHP at a COP of 2.5-3

 

 

Bin the MVHR. This will do your heat recovery and ventilation but recover the heat to the DHW rather than air. 

 

 

It should provide a cheap to install system especially in a bungalow.  ASHP beating running costs. Fast response heating with control from your phone built in. Free cooling in summer along with the PV. Plenty of fresh air. 

 

Put the rest of the cash into airtightness and insulation and you'll have a very warm and cheap to run house. 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Radian]

5 hours ago, Gill said:

No where near as much info available on A2A as ASHP so hard to get a good understanding of pros / cons / suitability

 

5 hours ago, Gill said:

A2A 
Pros

• Cooling  & Heating.  Cooling would work well with solar.
• Placement frees up wall space 

Cons: 

• No where near as much info available on A2A as ASHP so hard to get a good understanding of pros / cons / suitability
• Would MHRV system play nice with A2A?
• Require a separate solution for DHW
• Don't see this working with with ECO 7 tariff

I'm a recent convert. Nothing else quite delivers on-demand heat with a potential for COP 4 or higher. The closest would be ASHP with radiators but low flow temperatures limit the response time. Forget UFH unless you are prepared to have it running pretty much all of the time. Our A/C units are Daikin and they have a "Powerful" mode which, once activated, heats at full power for 20 minutes - but usually it gets too hot by then so we cancel it. This is one way to use it (when you only want heat intermittently) and works well with the scheduler which lets you set a minimum level for other times. Or you run the schedule as you would with any other space heating regime - i.e. timed for comfort at certain times of day and a setback for others. It really is incredibly flexible. And voice activated.

 

The downside of course is that it blows (warm or cool) air around the place and makes some noise to do that. Modern domestic oriented units are much better at this compared to the office style A/C of yesteryear. Occupancy sensors and directional vanes on some models will attempt to vector any breeze away from people. And noise levels can be controlled down to remarkably low levels.

 

What you would be advised to do is look at how you might site the indoor unit(s). The best arrangement is if they can be wall hung somewhere distant from where people sit. I have an 8.5m long room with a unit at one end and the most comfortable spot is at the opposite end. Not by a huge margin but noticeable. I think they suit open-plan layouts much better than individual rooms but with multi-split systems available, you can certainly use one per room.

[Gill]

12 hours ago, SteamyTea said:

As you have a suspended floor, it may be easier to insulate than you think.  Can you crawl under it?

 

Yes - we have crawl space under there and got 150mm omnifit wool insulation put in there back in October.  Not a job I fancied so left to the professionals.  In and out in under  a day and solid looking job to my untrained eye.  Didn't board under the wool - that's one that I'll maybe reconsider down the line but with questions about potential plumbing changes down the line, wanted to leave things reasonably accessible for now.  

11 hours ago, Iceverge said:

Bin the MVHR. This will do your heat recovery and ventilation but recover the heat to the DHW rather than air. 

 

 A new system enters the mix.  😀 I'll do some reading but meantime a few basic questions - I assume it should not be housed in a cold loft given it's recovering heat.  Cost wise, it looks like a very attractive option.  Does it partner up well with PV or would a 2nd system be required to act as a thermal store? 

 

10 hours ago, Radian said:

What you would be advised to do is look at how you might site the indoor unit(s). The best arrangement is if they can be wall hung somewhere distant from where people sit. I have an 8.5m long room with a unit at one end and the most comfortable spot is at the opposite end. Not by a huge margin but noticeable. I think they suit open-plan layouts much better than individual rooms but with multi-split systems available, you can certainly use one per room.

Thanks - this is one that I've been struggling with.    If I think about the currently problem areas...

• Kitchen has no heating and Kitchen to living room does not have a door.  We put up a heavy curtain for winter as it was leaching all the heat from the living area.  Ideally some heat in the kitchen would be good.
• Hall has no heating and suffers due to the porch being baltic and the internal door being a bit rubbish.  We do have doors between hall and living room so can shut up shop to avoid the worst of the heat loss.  I was thinking that a SH in the hall might be a good fit.  
• Bed 1 - rarely heat.  I'm thinking a backup wall mounted electric panel might do the job or if we went a2a and got the positioning correct, it would benefit.  If they are quiet enough to run in a bedroom then maybe that's an option too
• Bed 2 - With this one being an occasional room, i'm not sure what the best solution is.  The SH works pretty well here when it's used for WFH.  Not so good for guests as as SH overnight bakes you in your sleep.  
• Living area - Could potentially site something between the kitchen and the living room .  The space nearest the kitchen is used as a dining area.  The other option might be above the door at the end of the hall.  Would be close to my working from home area but might benefit the bathroom / bedroom more 

I've have a read about multi-split systems.

 

Thanks for all the input!

[crispy_wafer]

17 hours ago, Gill said:

 

A2A 
Pros

• Cooling  & Heating.  Cooling would work well with solar.
• Placement frees up wall space 

 

 

 

Another here who's having A2A installed upstairs (bedrooms) in our build.  Whilst we have no plasterboard in situ and good access to loft and spaces, 2 ducted systems, and a wall mounted unit going in.  Still thinking on what to do downstairs though, both for my pocket (Install, and monthly running costs), ease of use, least amount of faff, etc etc. 

 

[Iceverge]

2 hours ago, Gill said:

I assume it should not be housed in a cold loft given it's recovering heat.  Cost wise, it looks like a very attractive option.  Does it partner up well with PV or would a 2nd system be required to act as a thermal store? 

 

It slots in instead of your hot water cylinder.

 

It is a 270L unvented cylinder with a built in heat pump. It extracts air from the wet rooms in the house. As they will be at ~20deg you will get very good heat pump performance. Some units have a built in PV setting to take solar input to an immersion. Beware of the units you buy however as some need regular anode servicing. 

 

The downside is that you will be drawing in cold air through the vents in the windows/walls and any cracks in the building. Given that you will need holes in the house anyway it makes airtightness less critical than wil MVHR. 

 

This air will need to be heated up with another heat source. @Thedreamer uses a solid fuel stove but an A2A unit would work well too. 

 

As I understand it multi split systems are not as good as multiple single units. @Hanksy has some mitsubishi units if you search their posts. 

 

 

 

 

 

 

 

 

 

 

[Iceverge]

2 hours ago, Gill said:

 

 

I reckon an ESHP in either of the cupboards between the sitting room and kitchen provided that works in with your existing plumbing. 

 

Then 2* small A2A units in both of the bedrooms. And a slightly larger one in the sitting room.  Keep external units away from bedroom windows for noise. 

 

 

 

 

 

[Gill]

 

Thanks folks for all the input / advise.  Some more questions and a few answers .

 

 

 

7 hours ago, crispy_wafer said:

2 ducted systems, and a wall mounted unit going in

 

 

Curious - Is ducted system the same as the multi split system?   All new territory / terminology for me at the moment.

 

7 hours ago, Iceverge said:

It is a 270L unvented cylinder with a built in heat pump. It extracts air from the wet rooms in the house

So potentially a direct replacement for our immersion system and header tank ?  We use a shower pump for pressure - I assume I could continue to use that with the UVC?  

 

7 hours ago, Iceverge said:

Some units have a built in PV setting to take solar input to an immersion. Beware of the units you buy however as some need regular anode servicing

Solid advice - no one likes ongoing maintenance costs !

 

7 hours ago, Iceverge said:

The downside is that you will be drawing in cold air through the vents in the windows/walls and any cracks in the building. Given that you will need holes in the house anyway it makes airtightness less critical than wil MVHR. 

 

I'm wondering how this will work as we improve the air tightness.  The window replacements that will be fitted next month will have no trickle vents.  If we were to achieve improved airtightness, would condensation become an issue ? 

 

7 hours ago, Iceverge said:

@Hanksy has some mitsubishi units if you search their posts. 

  Some interesting reading in there on COP in the colder months.  

 

7 hours ago, Iceverge said:

I reckon an ESHP in either of the cupboards between the sitting room and kitchen provided that works in with your existing plumbing. 

 

The cupboard in the kitchen currently houses our immersion tank so that would tie in with existing plumbing. 

If i went A2A, are there any benefits to doing the ESHP at the same time?  Would be good to phase improvements but not if it incurs additional cost.

 

7 hours ago, Iceverge said:

Keep external units away from bedroom windows for noise. 

Positioning wise - is it one external to one internal ?  Similar positioning advise to ASHP, then the more sheltered and the warmer the location the better the performance?  The bedroom side of the house is south facing but is also close to neighbors with not a huge amount of space to the boundary - would need to have the units very close to the house in that area.     The opposite side (living room external ) has a lot more space but is a bit more exposed and doesn't get nearly as much sunshine.  Front external of the house doesn't get much light in the summer and frost can stay there all day.  

 

 

 

[Iceverge]

1 hour ago, Gill said:

So potentially a direct replacement for our immersion system and header tank ?

 

Yes, it is an unvented system so will require a pressure vessel too. Check your current plumbing is capable of mains pressure.

 

1 hour ago, Gill said:

We use a shower pump for pressure - I assume I could continue to use that with the UV

 

You can dispense with this as you'll have mains pressure hot water, a vastly superior experience. 

 

1 hour ago, Gill said:

Solid advice - no one likes ongoing maintenance co

 

Disclaimer, I've never used one, rather learned here about them. I like the theory however. A search of the term "ESHP" should point you in the right direction. You might fall in to G3 regs which technically require an annual check AFAIK. 

 

1 hour ago, Gill said:

If i went A2A, are there any benefits to doing the ESHP at the same time?  Would be good to phase improvements but not if it incurs additional cost.

 

 

Stand alone systems. No interdependence. 

 

1 hour ago, Gill said:

Positioning wise - is it one external to one internal

 

It depends, a multi split is one external to many internal. A simple split unit is one for one. More knowledgeable folk than me could point to the advantages/disadvantages of siteing close to the indoor unit. 

 

A warm location for an external unit is a bit mute given the enormous volume of air they move, so long as the fan isn't constantly fighting the prevailing wind or in a tiny alcove that will become refrigerated by the external unit you'll be ok. 

 

 

 

 

 

 

 

[Thedreamer]

@Gill Happy to answer any questions about our exhaust heat pump setup.

[Gill]

2 minutes ago, Thedreamer said:

@Gill Happy to answer any questions about our exhaust heat pump setup.

 

Thanks @Thedreamer

 

Would be great to get some general info on  your system setup... refurb or new build, pv hook up, ongoing maintenance, what was involved in your installation (more relevant if a replacement system but I'll take any info on offer), happy with running costs? In general how's the system working for you - anything you'd change if you were doing it again? 

 

It's all very high level questions but hopefully I'll get a bit more time to read up and ask some more specific questions. 

 

[crispy_wafer]

1 hour ago, Gill said:

 

Thanks folks for all the input / advise.  Some more questions and a few answers .

 

Curious - Is ducted system the same as the multi split system?   All new territory / terminology for me at the moment.

 

 

Yes, ducted just means the warm/cool air is delivered to the room via pipework and is sent into the room by grills or circular diffusers in the ceiling (normally), rather than physical units sat on the floor, high up, or ceiling mounted.  The bits that do the work are suspended in the loft.  Can be a multisplit, or non multisplit depending on how you want the system.  In my case I have a multisplit going in  Costing about 5,500 all in, which I think is in the right sort of ballpark, not cheap, but I'm doing this once and if it means the build takes a couple of months longer then so be it.

[Thedreamer]

3 minutes ago, Gill said:

 

Thanks @Thedreamer

 

Would be great to get some general info on  your system setup... refurb or new build, pv hook up, ongoing maintenance, what was involved in your installation (more relevant if a replacement system but I'll take any info on offer), happy with running costs? In general how's the system working for you - anything you'd change if you were doing it again? 

 

It's all very high level questions but hopefully I'll get a bit more time to read up and ask some more specific questions. 

 

 

We are a slightly higher building reg self build on Skye. Nothing fancy, just a modest three bedroom 138m2 completed in 2020.

 

Our installation consists of three extraction points in our en-suite, bathroom and utility this goes into a metal ducting into a mini air source heat pump on top of a cylinder. It takes that air and heats our domestic water (not heating) and blows cold air outside. It also extracts moisture through a pipe to the outside to help with humidity. 

 

It was quite cheap to install and is cheap to run. It's very consistent in the energy usage as it's not trying to take cold winter air outside like an external heat pump therefore always achieves a very higher cop.

 

Points to consider:

 

sound proofing - our sits in a cupboard in the utility room. No noise in the house, but when working its slightly louder than a fridge freezer. We have it on anti vibration mat. We also used flexible ducting just before it goes into the unit.

 

Get one with a good quality tank, some have anodes which require maintenance. A better quality one, such as a Joule cylinder does not.

 

Mostly importantly, as its sucking internal air into the system and this will pull cold air from outside. We manage this by having lots of south facing glazing which heats the house for about six months of the year and allows for a bit of this free energy to be sucked up into the system.

 

In the winter we rely on a centrally placed wood burner. Having access to free wood means that I can heat the house, with a few sticks and also the heat from the stove goes into the system. 

 

I am in an unique situation and if I did not have endless wood it might not be so attractive. That's not say it can't work efficiently in other circumstances.

 

With the £400 rebate and further expected £200 rebate as a non gas customer, we will have no energy bills for ten months. I don't have any solar panels at the moment, but might get some fitted in the future.

 

Here's my blog if you want to see pictures of the set-up.

 

 

[Radian]

22 minutes ago, crispy_wafer said:

In my case I have a multisplit going in  Costing about 5,500 all in, which I think is in the right sort of ballpark, not cheap, but I'm doing this once and if it means the build takes a couple of months longer then so be it.

 

Comparable, I'd say, to the real cost of installing a fossil fuel boiler and multiple radiators - especially if not on mains gas.

 

2 hours ago, Gill said:

Positioning wise - is it one external to one internal ? 

 

There are two main issues that I can think of. Obviously if there's only one outdoor compressor unit, then the indoor units can only cool or heat together. Less obvious perhaps is that the simultaneous heating/cooling capacity will be lower and all indoor units will go idle during defrosting mode. Neither of these is a show stopper but having one-to-one indoor outdoor units doesn't add a huge premium when most of the cost is in the indoor units. Here's the two outdoor units that provide us with a total of 7kW of heating for around 1.5kW of electricity. Quite a bit smaller than an ASHP and more practical to hang on a wall.

 

 

[Nickfromwales]

On 22/01/2023 at 22:42, Radian said:

And voice activated.

Voice-activated space heating...?

Hmmmm....

 

 

 

"Hey, Siri. I'm sweating my bollocks off here!".

[Nickfromwales]

On 22/01/2023 at 22:07, Iceverge said:

Bin the MVHR. This will do your heat recovery and ventilation but recover the heat to the DHW rather than air. 

110%.

MVHR here will be nigh-on useless imo.

 

On 22/01/2023 at 16:56, Gill said:

i'm sold on the broader benefits of MHRV even homes that cannot achieve great airtightness.

I turn these down tbh, as I know it's the wrong thing to do.

[Gill]

@Thedreamer thanks very much for all the info. I will work my way through it all (slowly as I'm still coming to grips with terminology). Your blog looks like a great resource too. Cracker of a house you've built.

 

@Radian sounds like multiple units would be a better option. Hadn't realised they could be mounted off the ground. I have much to learn! 

13 minutes ago, Nickfromwales said:

 

"Hey, Siri. I'm sweating my bollocks off here!".

Even if I maxed out airtightness & insulation, this will not be an issue for me. 🙂

 

 

11 minutes ago, Nickfromwales said:

MVHR here will be nigh-on useless imo.

I'm not tied to any solution - one small benifits of having no experience whatsoever in this domain. Key thing for me is the right system for our house. Maybe it will all become clear from reading more but how does fresh air get into the house with A2A or ESHP and how is condensation extracted? We have a condensation issue at the moment which I'm hoping new windows will help with but they won't have trickle vents. 

[Nickfromwales]

Devices which extract condensation have a condensate tray, this has a drain pipe, and this discharges the water to a drain.

 

You have 1g glazing atm, or 2g ?

[Gill]

7 hours ago, Nickfromwales said:

You have 1g glazing atm, or 2g ?

Currently 2G wood frames (no trickles). 

 

3G replacement getting fitted next month. 

 

[Nickfromwales]

56 minutes ago, Gill said:

Currently 2G wood frames (no trickles). 

 

3G replacement getting fitted next month. 

 

With / without trickles? 

[Gill]

2 hours ago, Nickfromwales said:

With / without trickles? 

Without.  Was one of the initial reasons I was looking at ventilation.  We have plenty unwanted ventilation at the moment but will be addressing that as we slowly update the house.

[SteamyTea]

Get the insulation and airtightness improved, then worry about ventilation.

I suspect that most of your condensation issues will vanish as you improve the basics.

Worth remembering that you never really get rid of mould. The fungal spores are ever present and just go dormant when the conditions are not right for them. Luckily what they hate, warm and dry, is what we like.

[Gill]

21 minutes ago, SteamyTea said:

Get the insulation and airtightness improved, then worry about ventilation.

I suspect that most of your condensation issues will vanish as you improve the basics.

 

 

Hmm - and I though condensation would get worse as we seal up the house.  Maybe I'm confusing this with air quality.

 

I was thinking that next up would be to sort out out bathrooms as our shower room has water ingress behind the tiles so will need to get stripped back. Plan was to rip that shower out and covert to WC and then add a shower into the other bathroom (which currently has none).   I figured if I knew the ventilation strategy I could sort this at the same time as the bathrooms and avoid any rework. 

 

An alternative would be fix the shower room that will eventually be redundant - figured that would be an unnecessary expense.  It would buy some more time to see how insulation and airtightness improvements affect the house and if i try to do it on a budget I guess I might learn how not to pasterboard and tile 🙂.   

 

[Nickfromwales]

1 hour ago, Gill said:

Without.  Was one of the initial reasons I was looking at ventilation.  We have plenty unwanted ventilation at the moment but will be addressing that as we slowly update the house.

Ok. I'm slowly coming back around to room by room ventilation ( via MVHR or other ). Detailing internal junctions ( if IWI ), eg where internal corners meet, where ceilings meet walls etc etc will be of absolute and critical importance here, or you'll get very localised issues where ( for eg ) dot and dab has bridged the covered cold wall to the interior of the room. This is something I have suffered myself, where I let dab squeeze between the insulation of the two abutting insulated plasterboards in my bathroom. You can literally draw with a pencil where I have done this as the damper part of the wall reacts after every shower is taken.

A sloppy installer will just bring the problems further forwards, so you need to vet the installer and be firm with what you expect from them, what the issue is that you're resolving, and how you wish to understand how it is to be carried out.