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So, what do you do about A/C?
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eric_2
Member Posts: 148
Thanks for the info. I appreciate the time. Looks like I might be investigating this option a little further.
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Comments
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-I believe it was Keven from N.H. a few days ago who stirred the pot by pointing out that forced hot air heat can provide comfort cooling a/c easier and cheaper than any other method. Hockey rinks are reverse radiant floor heating as DH exemplified in one of his hydronic books, but is that applicable for an in-floor hydronic radiant loop?
-what do you guys do about a/c? I live in CT where May through September, it is in season and desired--is it duct work for a/c and radiant and baseboard heat for heating, not that that is a bad option, but,
--what are the a/c options? If forced cool air, how do you sell it and get around the customer from just settling on forced hot air too and losing the radiant loops? I reallize you sell comfort, the 120* water temp is a plus too, but the duct work isn't cheap either...
Thanks, Ken0 -
What we did
We have steam heat and for our AC we installed two Unico systems (a high pressure/small diameter cooling system). It was a breeze to install in our old house. FWIW, they do offer a chilled water version zoned cooling. They are at http://www.unicosystem.com/0 -
A/
> -I believe it was Keven from N.H. a few days ago
> who stirred the pot by pointing out that forced
> hot air heat can provide comfort cooling a/c
> easier and cheaper than any other method. Hockey
> rinks are reverse radiant floor heating as DH
> exemplified in one of his hydronic books, but is
> that applicable for an in-floor hydronic radiant
> loop? -what do you guys do about a/c? I live
> in CT where May through September, it is in
> season and desired--is it duct work for a/c and
> radiant and baseboard heat for heating, not that
> that is a bad option, but, --what are the a/c
> options? If forced cool air, how do you sell it
> and get around the customer from just settling on
> forced hot air too and losing the radiant loops?
> I reallize you sell comfort, the 120* water temp
> is a plus too, but the duct work isn't cheap
> either... Thanks, Ken
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A/C with hot water heat
A high velocity air conditioning system is the best way
to go. Space Pak is the originator of the high velocity
systems. You can get information at www.spacepak.com/ .
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High velocity A/C is the way to go...
in most cases. It will provide good cooling, excellent humidity removal, and requires a minimum of house damage due to the small size of the ductwork.
We put Unico systems in on a regular basis in hydroniclly heated homes, and as long as the ductwork is sized and installed properly, they will work great.
Glenn Harrison, Residential Service Tech
Althoff Industries Inc. Mechanical and Electrical Services
Crystal Lake, Illinois
Althoff Industries website0 -
radiant cooling
works great. i run cold water through my radiant heating system in the summer and it cools my house to 70 degrees. the comfort level is unmatched. bobTo learn more about this professional, click here to visit their ad in Find A Contractor.0 -
high velocity a/c cost
How much does high velocity a/c cost vs. conventional? I asked a contractor who has installed them around here, and I think he said it was about three times the cost of a conventional system! Is the cost of the equipment really that much more?0 -
CONDENSATION
Do you run into any problems with condensation? I have all wooden floors in my house and am going to install radiant heat soon. Would love to do away with all the ductwork in the house.0 -
Bob G. Where are you located and how do you address humidity removal?0 -
Spacepak installation cost
Folks,
During February, 2002 I had a Spacepak system installed in my house. I have a two pipe steam heat system therefore, a high velocity system seemed like a good choice for A/C.
A. I had the system installed in the off-season, which gained me a 15 percent discount.
B. The system was sized at 3 tons (it was borderline between 2.5 and 3 tons based on cooling requirements for my home)
C. I'm feeding both the first and second floors with a total of 15 outlets.
Installed cost with an electrostatic air cleaner came in at $7,800. About two to three time the cost of an add-on to an existing forced air system.
D. A/C thermostat placed in upstairs hallway.
E. The system works extremely well, especially with humidity removal.
F. Installation went well. However, I hired one of my area's more experienced firms for the design and installation.
-Dave
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Cost of operation
Interestingly, the electrical utility cost of the Spacepak system is less than I was paying to run a dehumidifier in the basement and window A/C units.
I should include that fact that I have "interruptible" electrical service feeding the condensor, which is at a lower rate than the service feeding the rest of the house.
Now I cool the entire house instead of just a couple of rooms for less money.
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only 15?
For a 3 ton system 15 outlets seems on the low side, especially if you have some long runs to the first floor (assuming AHU in attic).
Check airflow at each outlet with turbometer, add them up and compare with specs.
Pay attention while operating with OAT in the low 70's and see if you aren't cycling on the freeze stat.
Mark0 -
conventional vs high-v
I've had two houses with separate heating and A/C systems.
One had scorched air heat and separate conventional A/C. The other has hot water w/ standing CI rads and separate SpacePak high-V A/C
Both cases the A/C air handler was in the attic, single return in upstairs hall, downstairs runs thru corners of upstairs closets. In both cases people would comment about how even the cooling was.
I have yet to find a house with a combined forced air heating and A/C system that does a good, balanced job of both heating and cooling.
The reason for choosing high-V was lack of space for conventional ductwork. Less labor to install high-V but not enough less to make up for increased material cost (don't think it's quite 3X however).
Mark0 -
15 outlets
My house isn't that large. It only measures out at 2000 sq ft.
My outlets are distributed as follows:
First floor: Kitchen (1), DR (2), Den (2), LR (3)
Second floor: Stair landing (1), North BR (1), Bath (1), Master BR (2), Master bath (1), South BR (1).
LR, Den, Master BR and South BR are on South or West side of the house. Other rooms on North or East side.
-Dave0 -
freezestat
Mark,
Where is the freezestat located? How might I check for freezestat cycling when outside air temp is approx 70 degrees F?
Thanks, Dave0 -
not size but airflow
You need airflow to keep evap coil from freezing. If I remember correctly, base guideline is 14 for 2.5 ton and 17 for 3 ton.
Long runs (over 15-20ft ?) must be de-rated. I have 17 terminations on a 2.5 ton unit but due to high plenum location in attic, many of the 1st floor runs are long. I've been having some freezestat cycling. Measured airflow and found I'm lacking. Will be adding some more runs this spring.
Mark0 -
freezestat
is attached to one of the loops on the end of the evap coil and enclosed in gooey insulation. It's wired in series with control wiring to condensor. When it opens, condensor stops but air handler fan keeps running.
Position yourself inside where you can hear both the interior circulating fan and the exterior condensor fan. If the condensor stops then restarts a few minutes later witout the interior fan stopping you're probably cycling on the freezestat (or the float switch which also indicates a problem requiring attention).
Mark0 -
Located
in New Jersey and humidity is removed by a dehumidifier. Not that there is a lot to deal with in the first place. For some reason I'm thinking that cold water cooling would create condensation. Am I completely off base in my thinking?0 -
freezestat cycling
When I'm up in the attic, there is no way to hear both fans at the same time. Any other suggestions?
I have one more opportunity to have the contractor/installer pay me a visit at no additional cost this Spring. It would be relatively easy to add a few more outlets, but would need sufficient justification.
-Dave0 -
You can check for a freeze
stat cycle or a float switch cycle with an electrical multimeter. Check for power between "Y" and common.
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Airflow
Mark,
Where to you measure airflow? At the return air intake? What device do you use and what is desired spec?
Lastly, how would you recommend I request this of my contractor?0 -
stay out of the attic
For me, the best place is to sit on the first->second floor stairs. I can just hear the condensor fan thru the wall, and can just make out the gentle woosh of air from the foyer termination located next to the stairs.
Since my White-Rodgers thermostat gives a resounding mechanical "snap" when turning on/off, if the condensor shuts off without a corresponding noise from the thermostat (audible from the stairs) I know the freezestat has opened.
Why not ask you installer to measure/compute total output with a turbometer and compare with the SpacePak specs and add additional terminations until it's in compliance?
Mark0 -
Good suggestion
This Spring, I'll sit on the stairs, as you suggest and listen to the White-Rogers. Sometimes it wakes me up at night if I'm sleeping light. I should have no problem hearing it (or not hearing it) during your recommended freezestat test.
Any suggestions on a different T-stat that is "quieter?"0 -
at the outlet
I borrowed a "vane anemometer" but don't remember the exact make/model. It had a head that resembled a box fan you'd find in electronic equipment - but with no motor. Turns out it was 2in diameter air path so setting it up to do CFM was pretty easy.
I measured CFM at each outlet and added 'em up. The installation manual lists the nominal airflow for each size air handler. I think the manual is available on spacepak's web site www.spacepak.com
Mark0 -
I find
that snap to be reassuring, and the W-R to be one of the more reliable thermostats I've had, so I've not investigated alternatives.
I'm sure other wallies will have suggestions - perhaps time to start another thread.
Mark0 -
I know I am the wrong Mark, but
The cheap down and dirty if you took algebra air flow device is made by (who else?) Dwyer. Used to be a model 410 air flow meter. Under $40. They now make 'em for kite fliers and sailors.
Mark
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i'm located in
northern mass. and i remove some humidity by also running the cold water through fan coil units with a drip pan underneath. 68 degree floors in the summer is a wonderful thing. bobTo learn more about this professional, click here to visit their ad in Find A Contractor.0 -
Dave
Don't get worried about nothing. You probably don't have a problem at all, unless the runs from the main duct to the outlet are longer than recommended. (I think 15' is the given measurement). Unico, much the same as Spacepak calls for 5 outlets per ton of condensing power. If your compressor was cycling off and on due to the freeze-stat, I don't think you would have seen a drop in your energy cost. Short cycling the compressor kills efficiency.0 -
Dave, Every manufacturer has a minimum # of vents needed.
Unfortunatly I don't have my reference material available as my truck is in the shop, but I beleive there is a minimum of 6 vents per ton of cooling. 6 per ton times 3 tons equals 18 vents MINIMUM for proper air flow, assuming that all the vents are within the "standard" length of the manufacturer. If the installer left the install books there, they should state the minimum number of vents per ton, and what is considered a normal length of run. If not, go to the website of the manufacturer of your indoor unit and look for the manuals or drop them a line explaining what you need to know.
Glenn Harrison, Residential Service Tech
Althoff Industries Inc. Mechanical and Electrical Services
Crystal Lake, Illinois
Althoff Industries website0 -
If your talking...
installing a High Velocity system from scratch as compared to installing an air conditioner on an existing forced air system, then 3 times is about right. However, if you comparing installing an air conditioner with an air handler and all the standard ductwork needed from scratch, as compared to a High velocity system from scratch, the costs should be about the same. The High Velocity system might even be less in some cases when you consider how much remodeling work might have to be done to install standard size ductwork.
Glenn Harrison, Residential Service Tech
Althoff Industries Inc. Mechanical and Electrical Services
Crystal Lake, Illinois
Althoff Industries website0 -
unico
I install alot of the units.You need to be careful and intall the mininum amount of diffussers per ton.Glen is correct,6 outlet per ton.Also most importantly check the ARI ratings for the condensor you use.A 12 seer condensor isnt allways 12 seer capacity on these units.You can get more cooling at times using a 10 seer condensor.
lol
Ray M
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At the outlet
Mark using a vane anemometer at the grille could and often does give you incorrect airflow readings as does a turbo meter.The correct way is to use a air capture hood and create a field ak factor. I typically find these meters to be off as much as 30-50% you have to use a hood.Once you have measured airflow at the grilles then measure your system delta-t at the grilles times your airflow, delta-t and SBTU factor of 1.08 this will give you your SBTU delivery into the conditioned space and compare to the equipment nomenclature.0 -
I'm having trouble imagining
a hood on a 2in termination for a high velocity unico or spacepak system :-)
Mark0 -
Mark your correct on high velocity a hood or any type of anemometer is not going to give you correct readings. The best way to dertermine airflow would be to measure static pressure then refer to the fan curve from the manufacture.0 -
unfortunately
SpacePak claims they don't have a blower curve available.
What got me started down this road was freezestat cycling during light load conditions. Checked static and it was running a bit high (1.75in with 1-1.5 the target) even though I had 17 terminations (no orfices) and 2.5ton only needs 14. Only other spec available was total AHU cfm was
to be 550cfm.
So I borrowed a Mannix DCFM8901 meter, measured flow at each termination and came up with a total of about 490cfm.
This is probably due to many of the runs being 20+ ft in length. It would explain the high static and freezestat opening under light load.
Mark0 -
Case for adding outlets
My system is still under first year warranty.
How might I make a case to have my contractor install additional outlets to match the Spacepak specs for minimum # outlets per ton?
I need some help here. I'm not looking for freebies. I just want the system installed properly and to spec.0
This discussion has been closed.
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