The simpler the better!

[Iceverge]

@WelshMatt welcome welcome

 

I like small houses. Good luck with your project.

 

On Woodburners.......

We're surrounded by trees here ( farm and woodland) . I spent 4 hours hanging onto the back of my Husqvarna yesterday. Not for firewood but just to clear fallen trees. I could probably spend 4 hours a day for the rest of my life doing the same. 

 

However we choose not to install a woodburner in our new house. (186m2 passive class) I really wanted one for ages too.  

 

The main reasons were. 

1. Air quality inside. ( lots of particulates from any solid fuel appliance) 

2. Labour, cleaning , dusting lighting. 

3. All or nothing approach to heating, either 5kw or zero or a very sooty fire. Unsuitable even in our previous badly insulated cold cottage as the living room would reach 25deg+ very quickly even on a cold day.  

4. They lead to poor airtightness. I'm yet to see one reaching passive house airtightness without very expensive continental spec stoves. 

5. With a very low heat demand the sums for the install cost alone didn't make sense vs a very cheap ( free ) electric rad. A nice stove and flue was costing about €5000 installed. Our heating bill was about €350 last year. Assuming you pay yourself any pittance to process firewood etc there's no saving in a low energy house. 

6. The risk of burning the house down. 

 

However if you're cool with all those things and maybe can put in a stove DIY ( can be done for £1000) you might like it. 

 

If it's in a central room it'll heat the whole house. We have no central heating as so long as the plug in rad is in any downstairs room and some doors are open the whole house is comfortable. 

 

@Thedreamer has a nice setup with an ESHP and a stove. The ESHP extracts internal air to heat the DHW so your ventilation air isn't really wasted. I would consider it. 

 

https://www.aircon.panasonic.eu/LV_lv/happening/new-panasonic-aquarea-dhw/ is an example. 

 

 

On the layout I would think about moving one bedroom to the west to minimise the internal corridor. 

 

If aiming for low embodied energy and low energy use in practice I would use a timber structure with plant based insulation like, cellulose, woodfiber or hemp, rather than oil based insulants. 

 

Good luck!

 

 

 

 

 

 

 

 

[WelshMatt]

58 minutes ago, JohnMo said:

I tried to extract from the bedrooms as that made sense to me as well, but the plans were rejected, so reverted to the normal supply.

 

With a Sip build you will be quite airtight without trying, so will have no option than go for MVHR.  The building regs do state balanced ventilation, so the option would need PIV and MEV or dMEV.  But that makes no sense, when you can recover the heat.

 

You could move air inside the house with dMEV fans within the internal walls.

Yeah I guess your right. Damn I hate Regulations haha. My only benefit of going the PIV route was to avoid all the nasty ducting that could potentially get clogged up with dust and hair over the years so I thought let's go with the more natural route of just using natural airflow like people have for hundreds of years. I can see that MVHR is more efficient in terms of energy use though as long as the heat recovery is as good as they say it is. I also think that when I open the windows which I will as I can't stand being stuck indoors with no natural airflow and open the doors for the dogs to go out all the benefits of the MVHR will be lost in a matter of minutes.

[WelshMatt]

48 minutes ago, ProDave said:

Is it wise spending too much time detailing the house until you have a plot?  I looked at 2 different plots and due to the different sizes, orientation and surroundings, the house I built on each would have been very different.

The house design is non negotiable. Its what I've always wanted layout wise and ease of use as I get older. I'll keep looking for a south facing fairly flat plot and until then I can wait and save more cash for the build.

[WelshMatt]

5 minutes ago, JohnMo said:

The extract points should be installed with a cone foam filter, that keeps the ducts clean

Ah I see. I'm guessing that those are just washable then and don't have to be replaced all the time right?

[JohnMo]

There about £3 each, not sure I would bother washing.

 

https://www.epicair.co.uk/products/extract-air-valve-filter-for-8960-125mm-valve-10-pieces

[SteamyTea]

32 minutes ago, WelshMatt said:

Thanks for this. Does doubling the size mean double the price

Probably not.

But you do not have to use pipework all the way.  It is just an airtight conduit that you need.  This is why, like PV, it is worth designing it in.

 

For ages I have been wondering how to plumb in (as a retrofit) MVHR.  Then realised I only need to go from the loft (where the unit will be) to upstairs.

The living room is connected to the landing via the open plan stairs (I (expletive deleted)ing hate this, makes the living room a corridor).

As I have a stud wall that runs from loft down to ground floor level, and an airing cupboard with the DHW cylinder in it, directly above kitchen, all I have to do is fit one extract pipe in kitchen to loft, then let the stud wall act as the other conduit for the incoming air.

[joth]

19 minutes ago, JohnMo said:

There about £3 each, not sure I would bother washing.

 

https://www.epicair.co.uk/products/extract-air-valve-filter-for-8960-125mm-valve-10-pieces

 

Interesting, our extract vents don't have these, I should probably look into this.

Is there anything specific needed to hold them in place or do the just sit loose above the adjustable vent?  How do you replace them without messing up the vent position/balancing?

 

[joe90]

The ridged pipe is quite smooth inside actually, our MVHR has been in two years and I am yet to replace/clean the filters (and we have a dog and a woodburner.). The room vents have a grill built in and these do need a clean occasionally (dust/static) . Having a woodburner is not about payback (IMO) it’s about the caveman feel and instant heat on those long winter cold days. 
 

58 minutes ago, WelshMatt said:

The house design is non negotiable. Its what I've always wanted layout wise and ease of use as I get older.

Good fir you, that’s what I did, I have had the design in my head fir many many years and luckily er indoors agreed.

[WelshMatt]

1 hour ago, Iceverge said:

@WelshMatt welcome welcome

 

I like small houses. Good luck with your project.

 

On Woodburners.......

We're surrounded by trees here ( farm and woodland) . I spent 4 hours hanging onto the back of my Husqvarna yesterday. Not for firewood but just to clear fallen trees. I could probably spend 4 hours a day for the rest of my life doing the same. 

 

However we choose not to install a woodburner in our new house. (186m2 passive class) I really wanted one for ages too.  

 

The main reasons were. 

1. Air quality inside. ( lots of particulates from any solid fuel appliance) 

2. Labour, cleaning , dusting lighting. 

3. All or nothing approach to heating, either 5kw or zero or a very sooty fire. Unsuitable even in our previous badly insulated cold cottage as the living room would reach 25deg+ very quickly even on a cold day.  

4. They lead to poor airtightness. I'm yet to see one reaching passive house airtightness without very expensive continental spec stoves. 

5. With a very low heat demand the sums for the install cost alone didn't make sense vs a very cheap ( free ) electric rad. A nice stove and flue was costing about €5000 installed. Our heating bill was about €350 last year. Assuming you pay yourself any pittance to process firewood etc there's no saving in a low energy house. 

6. The risk of burning the house down. 

 

However if you're cool with all those things and maybe can put in a stove DIY ( can be done for £1000) you might like it. 

 

If it's in a central room it'll heat the whole house. We have no central heating as so long as the plug in rad is in any downstairs room and some doors are open the whole house is comfortable. 

 

@Thedreamer has a nice setup with an ESHP and a stove. The ESHP extracts internal air to heat the DHW so your ventilation air isn't really wasted. I would consider it. 

 

https://www.aircon.panasonic.eu/LV_lv/happening/new-panasonic-aquarea-dhw/ is an example. 

 

 

On the layout I would think about moving one bedroom to the west to minimise the internal corridor. 

 

If aiming for low embodied energy and low energy use in practice I would use a timber structure with plant based insulation like, cellulose, woodfiber or hemp, rather than oil based insulants. 

 

Good luck!

 

 

 

 

 

 

 

 

Thanks for the info.

That DHW shows a 6.57kWh daily energy use. That can't be right can it!? It would cost a load to run that on the grid.

 

I had thought about a timber frame with hemp insulation but at least with a SIP it's made off site and just assembled at the build site so saves on labour costs plus as they use expanded polystyrene its only technically 3% plastic and doesn't have the risk of sagging and loosing efficiency over time like soft insulation does. Also there is much less thermal bridging compared to a timber frame build. 

[WelshMatt]

1 hour ago, SteamyTea said:

Probably not.

But you do not have to use pipework all the way.  It is just an airtight conduit that you need.  This is why, like PV, it is worth designing it in.

 

For ages I have been wondering how to plumb in (as a retrofit) MVHR.  Then realised I only need to go from the loft (where the unit will be) to upstairs.

The living room is connected to the landing via the open plan stairs (I (expletive deleted)ing hate this, makes the living room a corridor).

As I have a stud wall that runs from loft down to ground floor level, and an airing cupboard with the DHW cylinder in it, directly above kitchen, all I have to do is fit one extract pipe in kitchen to loft, then let the stud wall act as the other conduit for the incoming air.

That sounds like a good idea. I'm guessing that the stud wall would have a couple of vents in it to the rooms? I doubt planning would allow that in my case on a new build though unfortunately.

[WelshMatt]

35 minutes ago, joe90 said:

The ridged pipe is quite smooth inside actually, our MVHR has been in two years and I am yet to replace/clean the filters (and we have a dog and a woodburner.). The room vents have a grill built in and these do need a clean occasionally (dust/static) . Having a woodburner is not about payback (IMO) it’s about the caveman feel and instant heat on those long winter cold days. 
 

Good fir you, that’s what I did, I have had the design in my head fir many many years and luckily er indoors agreed.

Exactly, I've always wanted a woodburner so a woodburner is what I will have even if its rarely used. I don't see the point of buying an expensive ASHP that will cost a lot to run when I can have a Solar Assisted Heat Pump that has fewer moving parts to go wrong and only consumes 500watts when it's running for around 4 hours a day to get the hot water tank upto temperature. I'm sure if I can survive in my cold house now then whatever I get in the future will be a massive upgrade and cost less to heat.

[ProDave]

26 minutes ago, WelshMatt said:

I don't see the point of buying an expensive ASHP that will cost a lot to run when I can have a Solar Assisted Heat Pump that has fewer moving parts to go wrong and only consumes 500watts when it's running for around 4 hours a day to get the hot water tank upto temperature. I'm sure if I can survive in my cold house now then whatever I get in the future will be a massive upgrade and cost less to heat.

Why do you think an ASHP is going to cost a lot to run?  The amount of heat it needs to put into the house depends on your insulation and air tightness levels and your local climate.  Even up here in the much colder Highlands, and with a larger house than you are proposing, and with the now much higher electricity prices, my annual heating bill is just over £300  It would be a good deal less in a less cold climate and a smaller house. And that is keeping the house heated to 20 degrees all year.

 

Do you have a link to this "solar assisted" heat pump.  I am not sure it does have less moving parts than a normal ASHP, just different parts.

[JohnMo]

Basically no fans, instead of a radiator and fans it uses a couple of 2m X 1m black panels on roof or wall.

[JohnMo]

2 hours ago, joth said:

 

Interesting, our extract vents don't have these, I should probably look into this.

Is there anything specific needed to hold them in place or do the just sit loose above the adjustable vent?  How do you replace them without messing up the vent position/balancing?

 

You just take the whole extract nozzle out the ceiling, the filter cone goes over clips that are there already and slots back in place.  No need to move any adjustment parts.

[dpmiller]

25 minutes ago, JohnMo said:

Basically no fans, instead of a radiator and fans it uses a couple of 2m X 1m black panels on roof or wall.

that's one of them Spanish/ Portuguese things that doesn't work if it's cold?

[JohnMo]

I don't see the issue with them not working, the refrigerant is going in to the evaporator at minus lots, well below the coldest day.  So not different to ASHP.  The issue come when you try to run them as in warm climates, with just one panel on a 2kW unit. You need to use 2.

 

 

[WelshMatt]

1 hour ago, ProDave said:

Why do you think an ASHP is going to cost a lot to run?  The amount of heat it needs to put into the house depends on your insulation and air tightness levels and your local climate.  Even up here in the much colder Highlands, and with a larger house than you are proposing, and with the now much higher electricity prices, my annual heating bill is just over £300  It would be a good deal less in a less cold climate and a smaller house. And that is keeping the house heated to 20 degrees all year.

 

Do you have a link to this "solar assisted" heat pump.  I am not sure it does have less moving parts than a normal ASHP, just different parts.

£300 is amazing. I've been lurking on Facebook and people complain that theirs cost a lot more than that but I think they are retrofitted and not new builds.

 

Here's the link:

https://sahp.info/

 

It doesn't have the fan part just a compressor.

[WelshMatt]

52 minutes ago, dpmiller said:

that's one of them Spanish/ Portuguese things that doesn't work if it's cold?

I'm led to believe that it works down to the same temperatures as an ASHP.

[SteamyTea]

4 hours ago, dpmiller said:

that's one of them Spanish/ Portuguese things that doesn't work if it's cold?

The ones that have a panel from a domestic fridge as the collector.

They frost up and then absorb less, just like a freezer does.

Ice has a thermal conductance of 2.25 W.m^-1.K^-1 at -5°C.

Air, at the same temperature, is 24 mW.m^-1.K^-1

 

Edited May 5, 2022 by SteamyTea

[ProDave]

4 hours ago, WelshMatt said:

 

Here's the link:

https://sahp.info/

 

It doesn't have the fan part just a compressor.

Thanks.  Lousy website by the way, the only information of any worth is in the brochure that you can download.

 

My thoughts:  That system puts the heat exchanger panel on the roof and the compressor unit in the house.  Disadvantages. the pipework and gassing of the system has to be done by an F gas engineer so no DIY install possible, and it puts the noisy bit with the compressor inside your house.

 

On the other hand a conventional monoblock ASHP comes as a sealed system requiring just water and electrical connections, so perfectly possible for DIY install (many of us have done that) and it puts the noisy bit with the compressor outside your house.

[Simplysimon]

15 hours ago, WelshMatt said:

I want it to be as "eco friendly" as possible.The shell will be made from SIP panels

not exactly 'eco friendly' there are different insulators with better eco credentials and decrement delay. for all the cost of ufh pipes it is well worth considering doing

[Iceverge]

9 hours ago, WelshMatt said:

That DHW shows a 6.57kWh daily energy use

 

Ours is as close as makes no difference 3650kWh/year for 2 small kids and 2 adults or 10kWh/day. We heat a 300l UVC on cheap overnight electricity of 0.12c/kWh. (it was less than 10c) . Next year will cost us about €450. A DHW only heat pump would reduce this to about €180 or 3kW of solar PV with a diverter would leave us with only about €95 to top up with mains electricity. (This is the plan at some stage) 

 

Our total heating for the year was 3200ish kWh. If we had put UFH pipes and a willis heater like TerryE did we could have used night rate and the slab as a storage heater. As is we use a plug in rad, half the heating is on more expensive day rate, total cost about €480 for next year but the capital investment was zero. 

 

 

I would consider a split A2A unit for heating. ASHP performance but no pipes. 

https://www.orionairsales.co.uk/daikin-air-conditioning-rxm25r-ftxm25r-wall-mounted-25kw9000btu-inverter-heat-pump-r32-a-wi-fi-15085-p.asp

 

 

If you did want zero moving parts and a very robust system a stove and a direct cylinder with 2kw+ of PV and a diverter would be fine too. You would need to have the PV on a south facing roof/array to get any useful generation in the shoulder months mind you. 

 

11 hours ago, WelshMatt said:

Yeah I guess your right. Damn I hate Regulations haha. My only benefit of going the PIV route was to avoid all the nasty ducting that could potentially get clogged up with dust and hair over the years so I thought let's go with the more natural route of just using natural airflow like people have for hundreds of years. I can see that MVHR is more efficient in terms of energy use though as long as the heat recovery is as good as they say it is. I also think that when I open the windows which I will as I can't stand being stuck indoors with no natural airflow and open the doors for the dogs to go out all the benefits of the MVHR will be lost in a matter of minutes.

 

Have you considered the clogging of the PIV intake? The intake of our MVHR gets much grubbier than than the extract. 

 

I would be cautious of natural (hole in the wall) ventilation. It tends to be very drafty in windy weather and under ventilate the rest of the time with the associated buildup of pathogens, VOC's, mould, etc. It's the equivalent of having a hole in the roof for drinking water.

 

Am I correct in assuming your current lodging doesn't have a mechanical ventilation system of some sort?

 

[WelshMatt]

9 hours ago, SteamyTea said:

The ones that have a panel from a domestic fridge as the collector.

They frost up and then absorb less, just like a freezer does.

Ice has a thermal conductance of 2.25 W.m^-1.K^-1 at -5°C.

Air, at the same temperature, is 24 mW.m^-1.K^-1

 

Isn't that the same with a ASHP as well? 

I think that both systems have an automatic defrost cycle that they run through when they frost up.

[WelshMatt]

9 hours ago, ProDave said:

Thanks.  Lousy website by the way, the only information of any worth is in the brochure that you can download.

 

My thoughts:  That system puts the heat exchanger panel on the roof and the compressor unit in the house.  Disadvantages. the pipework and gassing of the system has to be done by an F gas engineer so no DIY install possible, and it puts the noisy bit with the compressor inside your house.

 

On the other hand a conventional monoblock ASHP comes as a sealed system requiring just water and electrical connections, so perfectly possible for DIY install (many of us have done that) and it puts the noisy bit with the compressor outside your house.

Fair points.

I'm not to concerned about the install as it's would be in a new build so I'd have to get someone qualified for the install to get the whole thing signed off anyhow.

I assumed that an ASHP also had some sort of pump indoors as well before the tank, is that not the case then?

 

Here's some information I had from the manufacturer on the differences between the 2 systems:

 

In that way, they share the same refrigeration principles as other heat pumps, the closest heat pump relative being an Air Source Heat Pump, however...
Where an Air Source Heat Pump has:
* A rotary compressor
* An enclosed finned tube heat exchanger (evaporator)
* A large fan to convect air over the evaporator
* A plate heat exchanger (condenser)
* A motorised valve
* And a pump to circulate water through the plate heat exchanger.

A Solar Assisted Heat Pump has only:
* A reciprocating compressor & an externally sited aluminium roll bond heat exchanger (evaporator)

 

This is why I preferred it as less moving parts to go wrong and their cheaper.

Edited May 6, 2022 by WelshMatt
Update

[WelshMatt]

8 hours ago, Simplysimon said:

not exactly 'eco friendly' there are different insulators with better eco credentials and decrement delay. for all the cost of ufh pipes it is well worth considering doing

What are the best ones that have no risk of 'sagging' over the years?

I guess sips aren't the best but there has to be a compromise along the way in terms of costs and build time. Unfortunately I won't have a massive budget and I'm not that good with my hands to take on a lot of the work myself.