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new heating system for doer upper

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  • 22-11-2020 2:19am
    #1
    declanobrennan
    Registered Users Posts: 190 ✭✭


    I've gone sale agreed on a complete doer upper- 3 bed terraced 2 story in Dublin City, about 70 sq ft - 1950s build, unoccupied for last 10 years.

    Everything was ripped out pre-sale; so no plumbing, heating, rads, boiler and will need complete new electrics.

    The downstairs floor is timber floorboards about 6 inches or more above a concrete foundation with space for ventilation. I'm planning on a Combi-boiler system.. MY question is, given I'm probably (budget allowing) going to be putting in a new floor with screed, insulation and DPM I was wondering how much extra will it be to install UFH then? Would I pay much more for UFH over the traditional radiators (probably four to five for downstairs) option (as well as four upstairs which I will even if I do go with UFH downstairs).

    Alternatively could I get away with just leaving the DS floor as is for a few years and just laying down carpet and installing rads and Combi-boiler? Or is this madness?

    Any advice appreciated. Thanks.


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    #2
    Calahonda52
    Registered Users Posts: 12,224 ✭✭✭✭Calahonda52


    Whats the wall buildup from inside to out?
    Are there wall vents?
    putting in the ufh piping is not a large addition expense on top of the screed, etc

    “I can’t pay my staff or mortgage with instagram likes”.



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    #3
    declanobrennan
    Registered Users Posts: 190 ✭✭declanobrennan


    Thanks for the reply. I don't think I had notifications on correctly for this thread, hence the delay in replying....

    I'm not sure what you mean by wall build up. I think it's brick with plaster and then wallpaper.

    I don't think there are any vents. Part of the reno plans.


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    #4
    Alkers
    Registered Users Posts: 6,815 ✭✭✭Alkers


    Replacing the floor is a now or never job imo, you're never going to want to do that once you're in the house as it's so invasive, I would do it beforehand. Not a massive fan of ufh myself but would still replace the floor


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    #5
    sydthebeat
    Subscribers Posts: 41,080 ✭✭✭✭sydthebeat


    UFH would be madness unless you plan to serious upgrade the insulation of the walls and roof along with your windows and air tightness to at least 2015 levels.


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    #6
    monseiur
    Registered Users Posts: 1,215 ✭✭✭monseiur


    With the house already gutted this is an ideal time to replace the floor with concrete screed on say 100mm insulation. If the existing timber floor is the original one chances are there is some dry rot, wood worm etc.
    If budget allows fit uPVC triple glazed windows & doors.
    Dryline all ''external walls'' with a minimum of 50mm insulated slab, some of the new electric wiring can be concealed under this slab.
    Fit a minimum of 300mm insulation in attic.
    Consult a good plumber before fitting underfloor heating - the jury seems to be still out on it.
    If downstairs ceilings are to be replaced ensure they're insulated/soundproofed.
    Once floor is in and first fix plumbing is done start upstairs and work your way down.
    If a new stairs is required don't fit until most of the demo/construction work is done otherwise it'll be a case of constantly.. 'mind the bannister son' !


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    #7
    declanobrennan
    Registered Users Posts: 190 ✭✭declanobrennan


    sydthebeat wrote: »
    UFH would be madness unless you plan to serious upgrade the insulation of the walls and roof along with your windows and air tightness to at least 2015 levels.


    Thanks. Well we're laying down rolls of insulation in the attic, redoing the internal stud walls (replaster, skimming) , and sticking on slabs of Kingspan on the front and back walls. Also all the old windows will have to be popped - they are lovely original wood frames but they are in rag order.

    The house is unoccupied for nearly a decade so there is a huge amount of work.


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    #8
    declanobrennan
    Registered Users Posts: 190 ✭✭declanobrennan


    Alkers wrote: »
    Replacing the floor is a now or never job imo, you're never going to want to do that once you're in the house as it's so invasive, I would do it beforehand. Not a massive fan of ufh myself but would still replace the floor

    Thanks. But what's the benefit of doing it? What's so bad with the old wooden frames over the old concrete slab and the gap in between? Is the benefit solely the heat insulation and the DPM?

    Why the reservation over ufh?

    thanks again, this is really helpful!


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    #9
    TheChizler
    Registered Users Posts: 9,428 ✭✭✭TheChizler


    sydthebeat wrote: »
    UFH would be madness unless you plan to serious upgrade the insulation of the walls and roof along with your windows and air tightness to at least 2015 levels.
    I've only heard people say that when combined with a heat pump, traditional heating would be fine wouldn't it? Or is it that the lower temperature of the floor compared to a radiator means you'd be losing the heat faster than the floor could deliver it?

    Following this thread closely, I'm planning a renovation in a >90 year old house so probably facing similar questions.


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    #10
    jmBuildExt
    Registered Users Posts: 692 ✭✭✭jmBuildExt


    As mentioned above by syd, the problem with ufh, in this particular application, is that the house will not be anywhere near the modern standards of insulation for you to get the benefit of it.
    Indeed, from the outline of your plan above, if you put in underfloor heating, the heat would simply be lost by conduction through the ground - you have a massive thermal bridge there..

    So as mentioned above, you need to be planning to insulate the slab below the UFH.
    In addition to this, in modern applications, there are other factors that can deal with heat loss via thermal bridge - e.g. a row of blocks that have low thermal conductivity.

    In summary, there is nothing wrong with UFH heating in principal, but in an old building, its not going to be efficient without major work, and you need to be concentrating on insulating the building and cutting out drafts before you consider UFH.


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    #11
    declanobrennan
    Registered Users Posts: 190 ✭✭declanobrennan


    thanks. I will defo only be putting in ufh with/after/ the new floor.

    In terms of the thermal bridge - is that the walls in between the houses? My surveyor had said there would be no need to insulate these walls. We are putting up slabs of kingspan on the back and front walls. It's likely though that I am misunderstanding your point...


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    #12
    sydthebeat
    Subscribers Posts: 41,080 ✭✭✭✭sydthebeat


    TheChizler wrote: »
    I've only heard people say that when combined with a heat pump, traditional heating would be fine wouldn't it? Or is it that the lower temperature of the floor compared to a radiator means you'd be losing the heat faster than the floor could deliver it?

    Following this thread closely, I'm planning a renovation in a >90 year old house so probably facing similar questions.

    UFH works on the principle of a constant comfortable temperature, which is created by using the high density elements of the build as a heat sink ie the walls and floors.

    maintaining a constant temperature will be very difficult if the build is drafty, thus the requirement to focus on air tightness of which decent windows are a significant part.

    however, reaching a comfortable temperature will be difficult if the insulation levels (along with air tightness) are not adequate.

    to the OP, you must be conscious that by using insulated boards internally you are loosing a significant area of those "high density" elements i referred to, and your only real heat sink is your floor screed. That means that your temps may fluctuate more than a contemporary UFH new build... and because of UFHs lack of speedy responsiveness, control over your heating may be difficult (high density elements help cool the build too by absorbing excess heat)

    also, sounds like a terraced house, are both houses either side occupied to a frequent degree?


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    #13
    Calahonda52
    Registered Users Posts: 12,224 ✭✭✭✭Calahonda52


    jmBuildExt wrote: »
    As mentioned above by syd, the problem with ufh, in this particular application, is that the house will not be anywhere near the modern standards of insulation for you to get the benefit of it.
    Indeed, from the outline of your plan above, if you put in underfloor heating, the heat would simply be lost by conduction through the ground - you have a massive thermal bridge there..

    So as mentioned above, you need to be planning to insulate the slab below the UFH.
    In addition to this, in modern applications, there are other factors that can deal with heat loss via thermal bridge - e.g. a row of blocks that have low thermal conductivity.

    In summary, there is nothing wrong with UFH heating in principal, but in an old building, its not going to be efficient without major work, and you need to be concentrating on insulating the building and cutting out drafts before you consider UFH.

    In fairness he did say he was putting insulation
    going to be putting in a new floor with screed, insulation and DPM
    and if he put a perimeter of 50mm XPS or whatever it would help.
    I agree the A/T and thermal mass are issues
    Combi boiler with UFH does not make sense, burning gas at maybe 2,000 to get water at maybe 80 to be cooled to say 28

    “I can’t pay my staff or mortgage with instagram likes”.



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    #14
    declanobrennan
    Registered Users Posts: 190 ✭✭declanobrennan


    sydthebeat wrote: »

    to the OP, you must be conscious that by using insulated boards internally you are loosing a significant area of those "high density" elements i referred to, and your only real heat sink is your floor screed. That means that your temps may fluctuate more than a contemporary UFH new build... and because of UFHs lack of speedy responsiveness, control over your heating may be difficult (high density elements help cool the build too by absorbing excess heat)

    also, sounds like a terraced house, are both houses either side occupied to a frequent degree?

    Thanks.. that is really informative. I've done a bit of reading around - not much - but that's the first I've heard about the high density heat sink factor.

    The homes on either side are occupied . An elderly couple on one side and on the other there is a single man (afaik and I haven't moved in, this is a new purchase of a house unoccupied for ten years). So not busy homes.....

    So do you think traditional rads are gonna be a more satisfying option?

    I assume any plumber I bring in to quote for this will have be able to give an objective recommendation? Certainly none. Of the builders that have quoted have raised these issues. I guess it's not their fortee.


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    #15
    Calahonda52
    Registered Users Posts: 12,224 ✭✭✭✭Calahonda52


    declanobrennan wrote: »
    1: I assume any plumber I bring in to quote for this will have be able to give an objective recommendation? Certainly none.
    2: Of the builders that have quoted have raised these issues. I guess it's not their fortee.
    1 wrong
    2: not interested

    “I can’t pay my staff or mortgage with instagram likes”.



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    #16
    declanobrennan
    Registered Users Posts: 190 ✭✭declanobrennan


    Calahonda52 wrote: »
    1 wrong
    2: not interested

    1. Thanks! So who can? Is it not in the arena of plumbing? Or do you mean that some plumbers won't have a clue and some will?

    I guess what I need is someone with the expertise in heating and plumbing and with objectivity - not some-one just trying to sell me UFH - to come in and have a look and be able to say, with all the other information about the house and my reno plans, yeah ufh/rads is what you want mate....


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    #17
    whizbang
    Registered Users Posts: 1,924 ✭✭✭whizbang


    Nobody mentioned considering External insulation...
    UFH would probably work well then.

    A lot of space lost on internal insulation, and then radiators loose even more.


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