Steam heated house need air conditioning
Hello, hope everyone is fine! What is the best way to air condition a house that has steam heat? Is it a big deal to do your own duct work and where do I find the spec’s to size it properly? Any ideas from your vast experiences. Thank you, Liam
Edited 5/7/2004 6:45 pm ET by Liam
Edited 5/7/2004 6:45 pm ET by Liam
Replies
Hi Liam,
Try an advanced search for "Unico" or "flexible mini-duct." Our c. 1913 house has hot water radiant heat, and we were loathe to lose any space to traditional ductwork. So instead we went with a Unico flexible mini-duct system. The ductwork can be snaked through joist and stud cavities.
It's significantly more expensive than traditional a/c systems, but there is a cost savings in that one doesn't have to build and finish soffits and other decorative coverings for the ductwork.
--Olsh
In Ontario, there are two predominant central AC options for homes with radiator heat: spacepak or split system. SpacePak is a tradename often used around here as the generic name for the flexible duct systems. I've never owned one and haven't scoured the website for sizing or installation. http://www.spacepak.com There is probably no better system in the world than radiant heat plus top-down AC. A reason around here for not choosing this is that old homes without ducts are similarly challenged for closets (where the small ducts hide).
Split system: compressor outside and inside unit - inevitably on the wall above the top of the stairs to the second floor - operated by remote control. Most 2-storey 3 bed homes have just one smallish unit, ~12 or ~15 thousand BTU/hr. For these, size charts are less important than the home's configuration; tall and slim is good. For sprawling ranch-style homes only, consider the multi-head systems. Start at http://www.mitsair.com.
I think good advice is to install a split-system (great value), and if really proves insufficient, resell it and go with the more invasive small duct system.
Just a HO, though - wait for the pros.
Edited 5/7/2004 9:50 pm ET by hacknhope
We have a small 1 1/2 story house. HW heat. I looked into the Unico, Spacepak, and a 3rd one (can't remember the name) 2 years ago.
9 grand.
Compared to $400 for a 10kBTU window unit and, well, the choice wasn't hard to make.
Though I do hate lugging that thing up each summer. If we stick around here for another few years, I might take a second look at the split systems again.
We are in that situation and evaluating split system vs CAC. All the CAC installers say our house (1929) does not need Unico/Spacepak, they will put in metal ducts hiding in closets. We have storage space in the attic.... Problems with Unico/Spacepak: (a) expense (b) intrusive (more vents needed per room) (c) it's got to be less efficient with the flexible hose (more friction).
I'm evaluating split systems right now, very tempting. Much cheaper than CAC, no wrecking crew, lower operating cost (cool one floor at a time). Disadvantages: mainly moving the air around, I can see the dining room an ice box while I'm cooking in my office. For upstairs considered through-the-wall fans but spouse nixed it on privacy concerns. That leaves portables for the bedrooms, we are medically unable to move window units in and out every spring/fall (and of course we're not about to leave them in year-round).
For retrofitting CAC: if you go this route I would use one criterion first for picking contractors: who do you trust not to destroy your old house in the process? Winnow out those that don't meet this criterion, then start arguing over size of unit.
And get lots of quotes, not mainly for price but for heat-gain calculations. I predict that they will be all over the map. I've found that even those claiming to do Manual/J are really just punching square footage in with everything else the same (insulation, window area, air infiltration, etc). The web sites that advise walking from HVAC contractor who does not do it right are useless; no-one does it right.
While I agree that the main drawback to the Unico system is the relatively high cost, the other two "drawbacks" you mentioned aren't quite the case. Three Unico mini-outlets serve each of the larger rooms in our house. They are 5" round vents which we had installed in the corners of the ceiling. Two vents are sufficient in the smaller rooms. But they blend in well with the ceiling. And remember, there are no added chases or soffits, which, to my eye, are much more intrusive than those little round vents.
As for the alleged inefficiency that comes from added "friction," the system uses a high velocity blower which stirs the room air and helps to remove humidity. (Unico claims their system removes about 30% more humidity from the air. I don't know if that's true.)
The point is to weigh each option on its true merits, as opposed to what negatives each vested interest has to say about the competition.
We've been extremely happy with our system so far.
--Olsh
Thanks for the update. Believe me I don't want to spread propaganda. I was advised against Unico because of cost alone, the rest were my surmises. Your points are well taken.
Not to resurrect a dead horse, but we are running into a strange phenomenon in our steam heated, 1914 house. We did the research on A/C installation do's and don'ts. Then invited some contractors to bid. Maybe it's Chicago. Maybe it's a seller's market. I have no idea.
The one with the stellar reputation (crew that isn't seasonal, gave ALL the right answers without prompting and then some, stellar references) gave a quote for $18K for Unico and (hold your hats) $28K for a forced air system. Trane and so forth.
10 year warranty as long as you keep up the service twice a year. At $300 per year.
I know that these ducts would be installed, taped and insulated properly. We hear such nightmare A/C stories in Chicago about bad ductwork, condensation, etc. etc.
I thought forced air was supposed to cost LESS than High Velocity. I looked him in the eye and asked him, "For a house that is 2200 sq ft where A/C would be used 3 months out of 12 TOPS...would you pay $28,000?" He looked downright depressed. (He is the son of the owner of the company...not that I want to stereotype...) He said, "All of our work is custom done by experienced professionals and well-serviced. We focus on comfort, not systems."
Sadly, the other contractors we talked to, while all over the place in price, seemed smarmy and unprofessional and inexperienced. This is like a bad set of blind dates.
I'd say "Eh!" and go back to using window A/C units for awhile except that we have had to gut the second floor due to old water and animal damage and mold. (Thanks PO!) And while these walls and ceilings are open, we need to pull the trigger.
Any suggestions for a gal in Chicago who just wants to keep cool this summer? Help? Luka? Andy? Darcy? Jaybird? Anyone? Help!
I'm frankly shocked that the Unico bid was 10K less than a traditionally ducted system. It seems to me to be a no-brainer. The Unico system, in my opinion, is more efficient, more comfortable and asthetically better. So why are you beating out your brains about the 28K side of the bid?
That ten year warranty also sounds a bit fishy, more like a service contract than a warranty. The equipment itself--i.e., the Unico air handler, and whatever compressor they go with, be it a Trane or another brand--carries a significant warranty already.
The real question is why that contractor is so much more eager to install a traditionally ducted system than a Unico system.
--Olsh
You might want to look at a ductless split AC system. A google should find some resources.
They have an outside compressor unit like a central system. But the inside units are a wall or ceiling mounted unit that is just the evaporator coil and fan. They need the connections for the freon tubing and a condensate drain, but no duct work. Some of them you can run 2 or 3 inside units off of one outside unit.
They are sorta of a hybreed between window units and central units.
Thank you, and thank everyone for the replies to my question of CAC in a steam heated house. My estimates for the large duct system was 26K using a geothermal unit. The duct work price was 10K. i am not a professional heating contractor but way above HO status as I have been working an rebuilding houses all my life, or 30 plus years. Design of the duct work system is my main concern. Again thank you all have noted an taken into consideration.