old house with 2 zones

[trenton_guy]

HI I may be replacing my 20+ year old Bryant split a/c ...I'm in a 50+ year old house and the original design was 2 seperate 2 ton zone systems ....wouldnt it be more efficiant if I can tie the duckwork together into one Big single zone system ? Is there any tricks used in the industry to tie the return vent and supply vents into one single zone ? If so are there things I need to look out for in terms of balancing the branches both verticaly and horizontaly ? Any tips you could offer or if you know of any web links where someone has written about doing that with their old house would be appreciated. The reason I'm thnking about replacing is because my upstairs system blows hot air ...ive checked the outside condensor,compressor,relays,capacitors as well as the indoor coil,fans and electirical...everything seems to run fine except its just blowing room temperture air. The last thing I intend to do is clean out the indoor coil with a strong vacumn and some of that coil cleaning foam. Does anyone have any thoughts about what the problem might be and if they think that coil foam stuff works ?

[dash]

If the upstairs blows a decent amount of air,it's not likely a dirty coil,as the air must go thru the coil.


Two stories two systems ,or IMHO, two zones system with one set of equipment.Like a Carrier Infinity with zoning.Without one or the other the up or down will be hotter or cooler ,summer vesus winter.

Ducts must be accessable to tie in to from one unit location.

Likely will only need 3.5 tons with one system,but have a load calculation done regardless.

[beenthere]

Instead of doing all these things and not know whats wrong, call a service contractor and have him check it, and fix it.

[coco]

would it be more efficient to turn a zone system into a single zone system? no . be cheaper to operate at your comfortablities expense. i have nothing against single zone systems they work great. start gettin into some BIG houses you need zones. a trick to tying the ducts together is ripping down all the old duct and installing the new single larger duct from scratch. if your upstairs heats are in the floor and run off of basement duct your ok. if u have a system in your attic with ceiling vents, no way to redo system without taking out floors, walls, and ceilings.
cleanliness is key. dirt is the #1 cause of heating, cooling problems. keep your indoor and outdoor coils sparkling as well as filters, it is $$ very well spent.
hot air coming out. something should be very obviosly wrong. overcharge? major duct leaks ?

[trenton_guy]

thanks for the responses ....do I take it that its agreed that I should stick with 2 seperate systems ...one for the first floor and one for the second ? by the way I have hot water baseboard heat so I'm only concerned about cooling. Dosnt the 2nd floor split system work harder then the first floor since heat rises ? assuming they are roughly 1000 cu. ft of living space per floor ...and assuming the upstairs will work harder should I do like 1 1/2 ton on the first floor and 2 tons on the second ? and secondly ....the 2nd floor unit that is blowing room temp. air has decent air flow so I guess that means its not a dirty coil issue. Could there be anything else or should I assume its a freon issue and call a tech. in ?

[beenthere]

Call a tech, he'll be able to find the problem.

Don't over size any a/c, exsrecially a second floor unit.
Stay with 2 systems.

If you over size the second floor, you'll have humidity trouble on both floors.

[coco]

what state u in? 50 yr old house id have my attic insulation professionally inspected and make sure those old ducts are nice and shiny on the inside. these are rough guesses only have so much info to work with trying to help. requsting a tech that has 15-20 yrs experience should be easily capable of helpin u out.

[trenton_guy]

thanks ...Coco the house has had recent blow in insulation added to the attic floor. The duck work is round flex insulated type. I'm curious .....where most often are leaks found ? in the evaporator ? The condensor coil ? or more often the run lines ?

[coco]

how many heats ? how many returns? sizes of all? nice smooth runs? sharp bends in flex is horrible. shouldnt run more than 10 feet of flex anyways per run, returns are more leniant. any longer should be hard r8 insulated pipe. can have a nice looking flex run that is hard to see but pinched off at its connection points make sure the diameter of space the air is allowed the flow though maintians a constant shape from duct to register.

[coco]

sorry from minnesota. when i say heats i mean supplies read you had baseboard heat

[dash]

Flex ducts need to be properly sized,as do all types of ducts,but their is no limit to the length ,as far as working properly.

[coco]

quit being cheap metal pipe is much better airflow than flex i wouldnt want 1 piece of flex anywhere in my house no limit to length? a 20 ft supply flex with a bunch of bends in it terrible airflow. how would you like a faucet that barely drips water

[dash]

1. A competent installer won't put unneeded bends in the flex.

2. If we design and install it ,the air flow will be the same or better than metal.



Just because you do metal,doesn't mean flex can't be done correctly.You don't see me condeming metal,and I've seen plenty of "bad" metal jobs.

"cheap is as cheap does"