Old house No insulation ,New hw boiler

GW

Got a guy with am 1880s house, needs a new oil HW boiler. An indirect will also be installed

The house has no insulation, except for a small bit in the basement ceiling. He says the energy auditor said walls can't be done, some sort of "back plaster" method that was the ticket back in the old days. He plans on adding insulation to the attic at some point. However my mission is to size the new boiler as is. It's a two family now, not huge, like 2500 sq ft, like an L style Cape sort of.

The cast rads are absolutely huge, I need to account for some extra mass.

Existing plant is two separate oil fired boilers with tankless . Two old boilers come out and one new boiler goes in.

I'll install an outdoor reset too, and gonna run a euro style constant

Just run the numbers and install the thing?

I am above average with wrightsoft, in my mere opinion anyway. I ran quick calcs and was a bit surprised how low the numbers were, but I had r19 attic. Got to click the no insulation button .

Thanks for the help. Looking for BTU comments.

Jamie Hall

Run the numbers and go for it. The energy audit bloke is quite right about the wall insulation -- trying to add almost anything stands a really good chance of blowing the plaster, which you really don't want to do. Hard to say exactly what the R value for the walls might be. 3 is probably too low. 5 might be about right, if infiltration is figured separately. How are the windows? If they are double hung in decent shape, infiltration won't be too horrendous. If he's got storms -- even the older triple tracks -- they will be pretty good, actually. The place I care for (see signature!) has a documented overall R value of 3.8 based on the gross wall and roof areas and on actual fuel usage. Very similar construction, only more of it, and with some roof insulation. You might be able to use that as a giggle check on whatever numbers the heat loss program comes up with...

And you would be welcome to come and visit this place to compare, if you would like. We're about an hour away from you.

GW

Jamie,

Nice thanks, what general direction, towards NY? Can't see the signature on my current media platform

I will specify the infiltration rate in my agreement, that is one number the homeowner has some control over. whatever the Loose ACH is will get typed in

Windows, so far I am running with a .56 U factor, which I am specifying. Perhaps I'll bump it up a bit.

I'm a bit knowledgeable with infiltration, have a blower door, spent time and dough with comfort inst.

Thanks Gary

Jamie Hall

@GW -- I've sent you a PM. Let me know if you don't get it!

JUGHNE

Just from being involved in remodels and rewiring for plaster & lath jobs....I am somewhat familiar with back plastering.

The intent of back plastering was to reduce air infiltration, in the 1880's they knew about infiltration/drafts, but the term R-value was probably not in the vocabulary yet.

So having back plastering the overall infiltration loss would be less......but probably not enough
Some back plastering was done in the middle of the stud space with the lath held away from the outside sheathing, which would give you 2 "dead" air spaces....between sheathing and back plastering and another space between the plastering and the inside plaster.
Have seen some plaster the sheathing first then do the inside center space and then the finish lath/plaster. Of course this gives you at least 16" of solid plaster clinkers at the bottom of the stud space. And the stud space may balloon 2 stories up to the attic. Some times the stud cavity extends up into the attic. (Rewiring from the top down without having to drill holes.....sweet)
If those exist then that is a great chimney of heat loss and easily corrected in the attic.

PS: for the sake of the science, Jamie's place would be a good study with a blower door test....

GW

Good info on the back plaster, was way before my time

JUGHNE

Before mine too! Just dealt with it as I mentioned.
Even saw a basement ceiling with it done....I think it was for a "cold" room for food storage.

GW

Yes I was trying to be humorous but my smiley face didn't go through. I've dealt with tons of stuff "before my time". Namely cast iron drains, old threaded water piping, old radiators, old all sorts of things. Old faucets...no thanks

Fred

GW said:

Yes I was trying to be humorous but my smiley face didn't go through. I've dealt with tons of stuff "before my time". Namely cast iron drains, old threaded water piping, old radiators, old all sorts of things. Old faucets...no thanks

That's just life's way of preparing you for the time when you have to deal with hateful old women. Ask me how I know.

GW

Just turned 50, I'm getting there.

Fred

I suppose life could just be preparing you for some of us hateful old Posters on here too, when you retire and have more time to spend here. LOL

EBEBRATT-Ed

Rewired a few of those places. As JUGHNE mentioned, sometimes with a two family you can drop a weighted string from the attic and find it on the cellar floor.

The other time not so much fun. Plaster clinkers between the walls fills in the holes when you drill up wire hung up snake hung up wire.....sucks