Heating system for 100year old house

50HX · 23-11-2020 7:02pm #1

Looking for some advice here

Doing up the home house at present

18" stone walls

Floors are coming up, reinsulate floor and ceilings
50mm ins slab on inside walls

Can't decjde on which heating system

Not a fan of a2w as i've seen similar house where a2w struggled to keep to temp and then no option of a boost

I was thinking zoned stove and oil boiler back up

Thought over the w/end to fit the pipe network for under floor heating( future proof) but if i'm doing that i may as well connect it.

Would under floor connect to boiler be a good option

Also is mhrv worth it in this type of house re mould/ventilation

If budget allows i'd like to install pv for electricity and hot water

sydthebeat · 23-11-2020 7:22pm

dont even consider A2W unless you can get your heat loss indicator down to at least 2.0

figure out what work youd have to do to your house to get it to that level (easy enough to do on paper)... then cost it up to see if its worth it economically to you.

if not, then consider other heat sources such a wood log gasification, if you have a decent site area and good storage

Calahonda52 · 23-11-2020 7:39pm

please describe the wall construction from inside to out?

50HX · 23-11-2020 7:47pm

Old quarry stone and house was plastered on the outside

I was expecting to meet some form of damp as it was built into a slope, the floor level inside would be 2' below outside ground level at the rear of the house

I have all that dug back and drain put in

Markcheese · 23-11-2020 7:55pm

Theres no wall insulation then ?
Those thick stone walls are good thermal mass , they hold heat well , and they seem better than just concrete but not really sure ,.
you should still be able to get good airtightness though ,
If youre putting in a wood stove can you get an external air supply for the stove ?

50HX · 23-11-2020 8:06pm

Markcheese wrote: »

Theres no wall insulation then ?
Those thick stone walls are good thermal mass , they hold heat well , and they seem better than just concrete but not really sure ,.
you should still be able to get good airtightness though ,
If youre putting in a wood stove can you get an external air supply for the stove ?

Plasterboards were put up but no insulation anywhere
I'm gutting the inside and changing the layout as functionally it didn't work as a house growing up.

Yes stove will have it's own external air supply

Calahonda52 · 24-11-2020 8:23am

50HX wrote: »

Old quarry stone and house was plastered on the outside

I was expecting to meet some form of damp as it was built into a slope, the floor level inside would be 2' below outside ground level at the rear of the house

I have all that dug back and drain put in

What was used to bond the stones, lime or cement?
Is the external plaster sand cement or lime?

50HX · 24-11-2020 12:23pm

Calahonda52 wrote: »

What was used to bond the stones, lime or cement?
Is the external plaster sand cement or lime?

Lime to bond inside

Sand cement then in the 80's outside

monseiur · 24-11-2020 4:15pm

Digging out floors to suit underfloor heating would mean going down at 8 to 12 inches which could destabilize the walls and chimney stack - depending of course on type of foundations etc.
But do fit underfloor insulation and reinforce screed / finished floor with steel mesh and ensure that you fit a strip of 50mm insulation between screed and external walls - this will meet up with dry lining on walls to ensure no cold bridging.
Also all pipe work for central heating will be under this floor screed.
Before fitting dry lining get professional advice on best practice in dry lining stone walls.
Fit good quality triple glazed uPVC windows and doors with trickle vents.
Fit at least 300mm insulation in attic.
You'll need an oil fired boiler as a back up to your solid fuel stove for central heating. Or consider heating domestic hot water only with stove (depending on output of boiler etc. a good plumber will advise you on this)
Fitting one or two PV panel on roof is not economical - you'd want to cover the whole roof with them !! and the pay back time is realistically 25+ years - some if not all may have to be replaced within that 25 year period. Get independent advise on this before proceeding - don't listen to sales men who have an obvious vested interest !

Calahonda52 · 24-11-2020 5:02pm

50HX wrote: »

Lime to bond inside

Sand cement then in the 80's outside

The outside sand cement is a problem in breathable wall.
I would look at EWI up into the attic and put in MVHR and have good airtightness

50HX · 24-11-2020 7:32pm

monseiur wrote: »

Digging out floors to suit underfloor heating would mean going down at 8 to 12 inches which could destabilize the walls and chimney stack - depending of course on type of foundations etc.
But do fit underfloor insulation and reinforce screed / finished floor with steel mesh and ensure that you fit a strip of 50mm insulation between screed and external walls - this will meet up with dry lining on walls to ensure no cold bridging.
Also all pipe work for central heating will be under this floor screed.
Before fitting dry lining get professional advice on best practice in dry lining stone walls.
Fit good quality triple glazed uPVC windows and doors with trickle vents.
Fit at least 300mm insulation in attic.
You'll need an oil fired boiler as a back up to your solid fuel stove for central heating. Or consider heating domestic hot water only with stove (depending on output of boiler etc. a good plumber will advise you on this)
Fitting one or two PV panel on roof is not economical - you'd want to cover the whole roof with them !! and the pay back time is realistically 25+ years - some if not all may have to be replaced within that 25 year period. Get independent advise on this before proceeding - don't listen to sales men who have an obvious vested interest !

Some great advice there, thanks
Have a friend selling pv and he told me forget it without a feed in tariff

Just wondering if my airtightness is not 100% will the ventilation part still work re preventing mould/water on windows inside??

50HX · 24-11-2020 7:34pm

Calahonda52 wrote: »

The outside sand cement is a problem in breathable wall.
I would look at EWI up into the attic and put in MVHR and have good airtightness

Ewi and insulated slabs work ok with old stone like this, does it not need to breathe one way at least?

MicktheMan · 24-11-2020 8:23pm

You can get breathable ewi systems

50HX · 24-11-2020 9:05pm

MicktheMan wrote: »

You can get breathable ewi systems

That i didn't know

Big money then to do both outside and inside insulation, offset it against a2w then i suppose

Will get it priced tho

MicktheMan · 24-11-2020 9:33pm

Don't do the iwi. The ewi should be enough if spec'ed / done correctly

Merrion · 24-11-2020 9:54pm

If it isn't a huge house then air-to-air heat exchanger is an option. It will keep the inside dry and so long as you don't have bad drafts it will be economical.

(If you have bad drafts, get that sorted regardless of what you heat with)

e.g. like [snip]

Calahonda52 · 25-11-2020 9:11am

Merrion, the link to your own personal blog, which has lousy cookie options, is, if I read it correctly, just a simple air con unit, which does nothing for ventilation, which is a key issue in this case due to the nature of the walls/

Merrion · 25-11-2020 10:00am

I have the same walls - 18 inch stone with no damp course (as the house is over 100 years old).

These houses were designed to be heated from a hearth and as long as you don't use impermeable covering (like cement plaster or foam insulation) the walls will "breathe" the moisture in/out.

If the walls are currently damp then I would look at what is causing that - remove any cement render and check the drainage of the land around the house (install a French drain maybe)

Markcheese · 25-11-2020 11:55am

Depending on the location of your fireplace ( or fireplaces ) , I think I'd look at one or 2 wood burners for your primary heat source ... ( Not really into back boilers but I'm open to persuasion ) ,
Maybe a wood pellet stove for the rads ect .. ? But i'd be piping for rads anyway ..even if fitted yet ..
I think I'd be concerned about interna wall l insulation as well .. you loose your thermal mass ,sand could end up with condensation/ mold behind the insulation
Air tightness and then some ventilation would be a priority ... External wall insulation could be done at a later date if the budget doesn't stretch ( it's outside the house after all )
I've heard of hemp/ lime plasters being used to give some insulation value , but I've no idea how effective they are , wether they're just for internal walls or what ..

50HX · 25-11-2020 10:56pm

Is mhvr the way to go to get good ventilation into the house

OH is insisting on it as she's lived in enough houses here with wet windows inside,moukd etc

I'll b 3glaze, insulated walls,floors&ceilings

MicktheMan · 25-11-2020 11:09pm

Depends.
MVHR typically goes into airtight new builds as duct runs to all rooms can be planned in advance.
DCV or MEV in existing houses because disruption can be far less.

50HX · 25-11-2020 11:11pm

MicktheMan wrote: »

Depends.
MVHR typically goes into airtight new builds as duct runs to all rooms can be planned in advance.
DCV or MEV in existing houses because disruption can be far less.

I'm gutting the inside fully, putting ufh and aluminium rads

MicktheMan · 25-11-2020 11:30pm

have you an air tightness target?

50HX · 25-11-2020 11:35pm

MicktheMan wrote: »

have you an air tightness target?

No i don't and don't know which system to go ventilate the house with

What would you recommend?

MicktheMan · 25-11-2020 11:58pm

50HX wrote: »

No i don't and don't know which system to go ventilate the house with

What would you recommend?

If you haven't already, I recommend you engage the services of a suitably qualified professional.

Boards can be great for general tips / advice / recommendations but I wouldn't be putting any value in specific advice from randomers on the internet, myself included, especially for an older stone building.

Having said that, if it was my gaff I would read up on air tightness, take it seriously, set a target of <1m3/hr/m2 and go with mvhr all the while cogniscent I was dealing with a structure that needs to be kept diffusion open (i.e. breathable). .

McOptimist · 26-11-2020 1:08am

Might be an option https://www.isover.ie/products/isover-vario-km-duplex-membrane

50HX · 26-11-2020 8:28am

I agree micktheman, just shooting the breezevon here a bit

My issue with professional services is that you talk 3 a d get 3 diff opinions of doing it

I'm happy with the heating& insulation route, it's the ventilation i'm stumped on

BryanF · 26-11-2020 9:31am

McOptimist wrote: »

Might be an option https://www.isover.ie/products/isover-vario-km-duplex-membrane

In a retro fit Scenario the vapour barrier/AIr-tightness membrane is not continuous

booooonzo · 26-11-2020 10:23am

BryanF wrote: »

In a retro fit Scenario the vapour barrier/AIr-tightness membrane is not continuous

it can be

BryanF · 26-11-2020 2:22pm

booooonzo wrote: »

it can be

Really? I’d like to see that

booooonzo · 26-11-2020 3:39pm

BryanF wrote: »

Really? I’d like to see that

yup, loads if you look about.

Heating system for 100year old house

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