Unsure about energy audit suggestions…
I apologize in advance for any length and confusion.
I’ll describe the house:
Location is Mid-Hudson Valley NY.
2 story colonial (I moved in about 2004). I think it had been built for someone else in 2003. Appx. 2300 sqft.
Attached 2-car garage, bonus room over garage, unfinished basement.
Central hydro air (oil boiler, indirect tank, air handler in basement & attic).
2006, an addition was built off of garage, resulting in a house that is now “L” shaped.
Being foolishly dumb, when the addition was added, I senselessly stood by as the contracted added yet another air handler system in the (unconditioned) bonus room along with another condenser? outside next to the other 2 units.
Anyway, after hemorraging oil these last few years, I got one of those NYSERDA audits. Here is some of what was recommended…
1. Attic air handler having issues – appx. $1300 diagnose & fix.
OR.
2. Replace unit ($6500 plus?)
3. Bigger oil boiler & 1″ pipes.
4. Seal, blow cellulose in attic, also spray attic rim joists, add door to concrete stair leading out to bilco door.
I said, hold on! I think I better do some research first. And so I found this site and did some reading.
Oh, and the way the addition was built, part of it has a flat ceiling, the other half a cathedral type ceiling. With recessed lights no less.
My questions:
I got another attic quote from a contractor who recommended open cell spray in the attic (about 7.5″, 3.5″ on the attic wall, about the same in bonus room and spray the bonus room floor).
Some questions:
1. There was no mention of spraying the rafters. Should I be concerned about that?
Also, they said they typically cut out the sheetrock from the garage and spray. Why would that be if the bonus room is unfinished? (I can move all my junk out of the room).
2. I asked what about the addition?
He said they could spray the half that they can get access to.
Does that seem sensible? Anyway, after hearing the price, I’m thinking I won’t be able to get all that done anyway.
3. In between the attic and the bonus room, there is a sort of crawl space where you can crawl through and jump right down into the bonus room.
The guy said they would seal off (leave it partitioned off) that space such that the attic & bonus room would be separate.
That would leave a unvented attic, a vented space about 6 feet long, an unvented bonus room.
Does that seem reasonable?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
This sounds like a train wreck. How did someone come to the conclusion that both the boiler piping and boiler are under-sized? Are you sure they're not confusing radiation with boiler sizing and piping? Is the boiler projected to be undersized even after the shell measures are complete? Anyone run a Manual J?
Do you have access to natural gas? If not, your 2 major priorities will be 1) transitioning away from oil to high efficiency air-source heat pumps, and 2) aggressively treating or eliminating the duct-work that is outside conditioned space.
If it were my job I would probably start by removing the hydro air coil from the downstairs system first, and replace it with an air source heat pump. At the same time, look for opportunities to serve some of the upstairs room using this duct system. Then possibly add ductless minisplits to the remaining upstairs rooms. Consider using the Bryant Evolution Extreme/Carrier Greenspeed Infinity.
Louis,
I agree with Jesse that it makes no sense to buy a larger oil boiler. (Has the existing boiler had trouble keeping up with the heating load?) Since oil is an expensive fuel, it makes more sense to invest in new heating equipment with a less expensive fuel.
It's hard to visualize all of the building envelope problems you describe, but it sounds like your house is a candidate for blower-door directed air sealing. You can't improve the thermal envelope of your home until (a) The location of the air barrier is clearly defined; (b) All air barrier defects and discontinuities have been remedied; (c) You make sure that there is a thick layer of insulation that follows the air barrier.
Louis ,
Any heating system work should be preceded by a detailed room by room heat loss calculation , no matter what type of heating you have . It could be as simple as ( not simple ) the boiler is sized properly but the ducting is grossly oversized and the loss of thermal content within it is too great . I suggest contacting a reputable , knowledgable person in your area to do a true fact finding evaluation and then make suggestions and recommendations . Whereabouts are you , mid Hudson valley is quite vague . Maybe there is someone that could be recommended or a direction in which you could be pointed in .
I dug up the paperwork that the energy survey people gave me to take a look again. The guy did do a blower door test ( this was a couple months ago I think). The paperwork mentions several suggestions broken up into building envelope & equipment.
The envelope suggestions and quotes are for either sealing and blowing cellulose or spray (I guess since there are 2 air handlers and ductwork in unconditioned space).
Actually, there are 3 air handlers. One in the unfinished basement, one in the bonus room/attic, one in the attic.
I spoke again with the guy recently and asked about the boiler suggestion. He said the air handler in the attic is not performing (blowing luke-warm air) and suggested that either it's not getting enough BTU --thus the piping and boiler suggestion, or there is a problem with that air handler.
The guy is supposed to be from a reputable heating/plumbing place.
I went online to do a heat loss (build it solar.com I think) and tried to do the heat loss myself. Unless I'm doing something wrong the numbers suggest a heat load of about 86,000 btu. The numbers I come up with the upstairs part of the house read something like 27,000 btu. I looked at the sticker on the air handler in the attic it looked up info on it and from what I can tell that model air handler seems to have numbers that say about 40,000 btu.
I don't have any problem with the boiler putting out heat either to the downstairs or the addition.
In retrospect, I'm thinking they could have run both the upstairs AND the addition off of just that one air handler. But I don't know what effect the attic has as far as extra load.
But the advice I'm reading here (and previous blogs) suggest concentrating first on the envelope. So I asked the guy for some clarification. He said the attic does not have enough insulation so that's why they suggest sealing & blowing cellulose. But that the quote does NOT include the addition. Apparently the cathedral part of the sealing in the addition presents access problems.
I told him I have to think about it. I can't get all this done at once and I'd like to concentrate on what's most important first. I had a lot of ice damming this past winter.
By the way, I'm in Orange County NY (Bloomingburg). Near the border of Sullivan county. About 40 minutes NW of West Point.
A larger oil-boiler may get rid of the tepid-air condition, but it's not the "right" solution any more than having THREE hydro-air air handlers in a 2300' house is. It could be as simple as fixing the duct leakage, unless they were tested and found to be tight.
A heat load of 86,000 BTU/hr @ 2F (nearby Newburgh's 99% outside design temp: http://www.energystar.gov/ia/partners/bldrs_lenders_raters/downloads/Outdoor_Design_Conditions_508.pdf ) for a 2300' house comes out at 37 BTU per square foot of conditioned space. I'm not saying that's impossible, but that would be more typical of an uninsulated 2300' house with single pane windows and lots of air leaks. (Most code-min 2300' houses in Fairbanks AK don't have a heat load that high even at a design temp of -41F.)
But the 27,000 BTU/hr number is credible, which would make ANY oil boiler at least 2x oversized for the actual heat load.
The BTU output numbers on the air handler itself are a specification for it's performance at a specified input water temp & flow (the pump impeller could be toast and only delivering 0.5 gpm for a coil specified at 4gpm), and are normally oversized for the space heating load by at least 1.5-2x if 180F water is specified, and would still be able to deliver the heat using lower temp water, which is useful when you have a condensing boiler, not so much with an oil boiler. As long as the coil in the air handler is getting at least 140F water the exit air should have a temp of something like 115F at the air handler, maybe 110F at some remote register, either of which would feel warm, not tepid. (I have a hydro-air zone at my house with ~120-125F water and it delivers 100F+ air at every register, but both the air handler and ducts are fully inside the insulation, not in a cold attic.)
If the ducts & air handler are in the attic above the insulation (especially if not well sealed & insulated) that's an issue in itself, adding to both the heating & cooling loads.
At the recent-years price of oil & electricity (as opposed to what it was in 2002-2004) it's almost cheaper to use resistance electricity to heat your house, but definitely cheaper to heat with heat pumps. But before doing ANYTHING to the mechanicals it's important to understand where the heat losses are and fix what's reasonable.
More than just a heat loss, the recessed lighting in the cathedral ceilings are likely to be moisture-injecting air leaks compromising the roof deck, as well as ice-dam trigger points. It's worth yarding them out and replacing them with surface mounted fixtures (flat, pendant, or other), insulating & air sealing where they were. Or, you could pull them out completely and light the space with wall mounted upward directed cove-lighting reflecting off the ceiling, which has lower glare and higher visual efficacy than any down-lighting solution. Think about it.
Is the foundation insulated?
What was the cfm/50 number on the blower door test?
Dana,
The foundation is not insulated.
The blower door test was 5200 cfm50.
I am inquired into a couple of insulation contractors to get an estimate between sealing-cellulose and spray foam.
I should clarify that the house was originally 2300sq rectangular shaped. Then an addition was added (about 900sq) off of the garage so that the house is now shaped like an "L". Thus the total sq ft had been increased to appx. 3100sq.
It was when the addition was added that the 3rd air handler was added.
I'm intrigued by the idea of the new efficient heat pumps I've heard about. But currently the oil boiler supplies heat & hot water via the indirect tank.
I'm not sure what kind of efficiency to expect by a heat pump that's added to the current ducted system? Also what the cost of a new setup would be in terms of payback period?
A question to anyone.... If spray foam should be sprayed on the rafters, how is it that people are able to add sheetrock? Like for instance as a vapor barrier or finishing the bonus room?
Louis,
A rough calculation:
If your area is 3,100 s.f., then your volume is about 24,800 cubic feet (unless you have high ceilings).
That would mean that 5,200 cfm50 = 12.5 ach50.
That isn't unusual for an older house, but it's pretty leaky. I am repeating my earlier advice: your home would benefit from blower-door-directed air sealing.