(Heating, Ventilating, and Air Conditioning) For questions about installing, repairing, and troubleshooting HVAC systems.
4
votes
2answers
5k views
Workarounds for single-zone HVAC? Second thermostat? Adjust vents?
I have a two story brick home built in 1970 with a relatively new HVAC system blowing through original ductwork. In the summer its too hot upstairs and too cold downstairs. I know that the full ...
4
votes
1answer
468 views
ductless AC split systems?
Does anyone have the ductless split AC systems offered by Mitsubishi, etc.? Is installing them a DIY job? Can you share your comments about them, in general?
Edit: Inspired by DA01 comment, I'd ...
4
votes
1answer
721 views
What's wrong with my thermostat (fan / limit control)?
I previously asked about wiring the White-Rodgers fan/limit control on my wood stove.
It's now wired and the wood stove is fired up. I ran the fan wires to the fan (hot) and I capped the limit ...
4
votes
1answer
74 views
Connection for C wire on Mastertrol Mark V zone control panel
I have spent hours searching the web for information on this 20+ year old zone control panel, which supports 3 zones of Heat and A/C.
The thermostat I'm replacing (on Zone 3) connects to T4/T5/T6 as ...
4
votes
3answers
503 views
What's causing the rumbling sound when my furnace kicks on?
I have a new, 3-year old, high-efficiency furnace in my home. Last year it started making a slight whining noise that was audible during the very first stage, before the blower motor started. No ...
4
votes
2answers
460 views
What are effective ways to frame a return air duct?
Consider an in-floor return air duct that is 32" x 22".
A standard air filter that closest fits the register is 30" x 20".
What materials should I use to frame the duct so it will snugly hold the ...
4
votes
1answer
362 views
two condensate drains?
we just had a new AC system installed in my florida house. the unit is in the garage, and the air handler is vertical with the evaporator on top.
the unit he removed had 2 condensate lines: one that ...
4
votes
3answers
295 views
How can I redirect the discharge of my forced air vent?
An AC/heating register on our kitchen ceiling blows air directly toward a gas cooktop causing the flames to flicker. Adjusting the register doesn't seem to make a difference. I've looked into air ...
4
votes
2answers
330 views
Can an HRV replace the air exhausted by a range hood?
I'm in the process of buying a 1950s ranch house. It doesn't have the greatest insulation, so I'm planning to do some improvements over the first few years to tighten things up. I'll certainly do the ...
4
votes
1answer
777 views
Adding AC to forced air system
We have an old house that happens to have forced air. Unfortunately, according to an HVAC tech it looks like there aren't sufficient return vents to add a compressor to our furnace.
I guess I'm ...
4
votes
1answer
437 views
How can I prevent my HVAC condensate drain line from freezing?
Last night, my heat (forced air) suddenly stopped. Today, a plumber figured out that my heater is 90% efficient, produces lots of condensate, and the drain line had frozen. We went outside and saw ...
4
votes
1answer
1k views
How should one size ductwork for a new air return duct?
I recently had a contractor build a wall which split one room into two. The new room is an office with two computers, and four monitors. It gets very, very hot, until the air conditioning turns on, ...
4
votes
1answer
272 views
What could cause a furnace to short cycle?
My Ducane MPGA100B4B furnace is shortcycling (2 minutes from fan on to fan off)
The thermostat's Heat Anticipator setting doesn't seem to matter for the on-time, maybe the offtime changes
The ...
4
votes
2answers
590 views
Where should I install a Pellet Stove to supplement my boiler?
We are purchasing a pellet stove insert for our single floor 1200 sq. ft. home. We are doing this to reduce our dependency on oil (hot water boiler), which we use to heat the house with baseboard hot ...
4
votes
0answers
101 views
When cleaning HVAC ducts, is treatment for fungi and bacteria routine and mandatory after 20 years? [closed]
Is treatment for fungi and bacteria routine and mandatory after 20 years? Or should we test for fungi or bacteria first? This would be in addition to air duct cleaning.
3
votes
6answers
2k views
Would putting a sprinkler on my roof help cool my home?
Anyone ever put a sprinkler on your roof to help out your A/C on unusually hot days? Just wondering if it helps.
3
votes
3answers
4k views
How much less power does a three-phase A\C unit use as apposed to a 220v unit?
I'm planning to install a 5 ton central AC. I'm deciding between a condensing unit that runs on 220V and a costlier unit that runs on 207Y three-phase.
My understanding is that three-phase motors use ...
3
votes
4answers
335 views
Air conditioning on a shoestring budget
Without purchasing expensive air-con units, or solar panels - and the associated moutings and electrical paraphernalia, is it possible to create a temperature difference of 10-20 °C using materials ...
3
votes
3answers
1k views
Can I sense filter replacement need based on filter pressure drop?
I should first point out that the system I'm referring to will be a self build DIY project. Fan and Filters being the only items purchased complete, And I'm still in the design phase but I'm not a ...
3
votes
3answers
102 views
Geothermal Resources
I am very interested in learning more about Geothermal solutions for my house.
What are the best resources for learning about and planning a Geothermal systems for a residential house?
Also, does ...
3
votes
4answers
3k views
How often should I run a bleach and water solution through heat pump lines?
How often do you need to run a bleach and water solution through the heat pump lines to keep the bacteria away?
What are the recommended parts (e.g. 1 part bleach, 10 part water) ?
3
votes
2answers
289 views
Why is my furnace filter alarmingly clean?
I have central air and heat at my appartment I moved into about 6 months ago. Today I decided it was probably long past time to figure out how to change filters in the furnace so I poke around until I ...
3
votes
3answers
142 views
How can I repair these rusty electrical connections?
When I turn on my air conditioner at the thermostat the vents kick on but nothing outside. Also the last time that it worked it took a few minutes to get going and was pretty loud. I checked the ...
3
votes
1answer
1k views
Convert line voltage heating system to use low voltage thermostats
I currently have two line voltage ceiling radiant heating systems in my condo each with their own DPST thermostat. I'd like to use low voltage thermostats such as the nest. I found this ...
3
votes
2answers
899 views
Can I increase air volume by adding more fans?
I have a straight 25 foot rectangular duct that is 0.9 sqft in cross-sectional area (11" by 12"). There are openings on either end, and nowhere in the middle. I wish to move about 1000 CFM through the ...
3
votes
2answers
1k views
Is a lip necessary on an HVAC ceiling register boot for use with flexible ducting?
I've installed some new ceiling register boots to use with flexible ducting and realized after install that they have a smooth connection with no lip. I'm assuming they are made for metal ducting, as ...
3
votes
1answer
194 views
How do I support vertical runs of round ducting?
Supporting ducts horizontally seems pretty straight forward--just a loop of strapping underneath to support it. What about when the duct runs vertically? Do you use the same kind of strapping but ...
3
votes
2answers
181 views
Can a HVAC solve my ventilation problem?
I have a problem with my house such that with all my windows and doors closed the house smells and the air feels stale. I'm thinking of purchasing a high efficiency HVAC to vent the stale air out and ...
3
votes
2answers
907 views
Should my thermostat's blue wire be going to W2?
I've recently moved into my first house and am looking to replace the existing basic thermostat in the home. Here is a picture of how I found it wired:
Researching the wires, I've read that ...
3
votes
1answer
239 views
Is it OK to shut off the A/C at the breaker?
My A/C continues to run even after the thermostat says it should shut off. Can I shut off the A/C by tripping the circuit breaker until it can be looked at? Is there any safety issue with doing this?
...
3
votes
3answers
1k views
Can I using a 3-phase connection to power 1-phase AC unit?
I have preparation for an AC connection with 3-phase 220V 3X16A breaker. I want to install a 220V 1-phase unit, which also needs a 16A breaker. The physical connection has screw-on terminals, so there ...
3
votes
1answer
83 views
It is reasonable to expect a contractor to replace the last foot of HVAC duct work, the connection between the insulated duct and the register?
The contract was to replace an antiquated HVAC and duct work. Since the registers are a standard size, would this connection also be a standard pre-fabricated part?
What is that last connection ...
3
votes
1answer
191 views
Improve AC flow to secondary ducts
I have an AC which has 3 ducts coming out of it. Only one duct gets flow - I'm guessing the AC fan blows right into it. What can I do to improve the flow?
3
votes
2answers
2k views
How do I install a jump duct?
Our master bedroom is considerably warmer than the living/dining/kitchen area of our house, and we've been setting the thermostat quite lower than we'd like in order for the bedroom to get cool enough ...
3
votes
1answer
142 views
How to find this particular hot water heat pump?
I have this pump pictured attached to my furnace. I actually have two of them. This one, however, is on a circuit that has been empty for a few years and is now rusted shut and needs replacing. I have ...
3
votes
3answers
12k views
Why is my furnace blowing cold air?
My HEIL 7000 natural gas furnace has stopped working what are the most likely causes, and how to verify faulty parts?
Normal operation routine
Thermostat sends "need heat" signal.
Exhaust blower ...
3
votes
1answer
71 views
How do I install a bathroom exhaust system?
We are set to close on our house in about three weeks and one of the problems that the inspector noted was that the vent in the guest bath vents into the attic (never going outside) and the master ...
3
votes
1answer
57 views
Does code require the gas line to be replaced when replacing a furnace?
I replaced my 45 year old (still working) original furnace with an American Standard furnace about 5 1/2 years ago. Now I have a gas leak; the Nicor technician sealed a connection in the gas pipe ...
3
votes
1answer
79 views
How do I provide proper fire protection in this situation?
HVAC guys are running a vertical duct (supply and return) from my basement to my 2nd floor attic. It will run adjacent to an exterior wall and will eventually be enclosed in a drywalled-in vertical ...
3
votes
1answer
386 views
How do I replace an A/C diffuser attached to flex duct?
Our house has central air, with the air distributed via flex ducts around the house. On the second floor, the diffusers have baffles behind them that can be closed when the system is not in use, but ...
3
votes
3answers
1k views
Why would a furnace overheat with a standard density filter?
Some time ago I found my furnace (gas, forced air, downdraft) was getting stuck on, blowing cold air. I could reset it, but it would happen again after a while.
After calling out a service man, I ...
3
votes
1answer
3k views
How should I wire this White-Rodgers fan and limit control? What about the thermostat?
I have a wood-burning stove, that is used as an auxiliary heat source in the house. There's a regular electric furnace, and adjacent to it is the stove. The warm air duct (out) from the stove ...
3
votes
1answer
157 views
Is it normal for air to be leaking from where the drain hose connects to the central A/C unit?
I'm trying to determine if I have a leak around my central AC unit. Basically when the unit is on, I feel cool air blowing outside the "furnace plenum" as I believe its called.
If you look at this ...
3
votes
1answer
254 views
How can I protect A/C condenser wires?
I bought a replacement condenser fan motor for my outdoor A/C unit. The old unit was CW direction only. This one is CW/CCW and has 4 wires stick out of the side that change direction depending on how ...
3
votes
0answers
44 views
Why won't the fan run independently of the air conditioner?
I have central air and heat, with a Nest thermostat. My system has Y, G, R, C and W wires coming out of it:
which are wired into my Nest like so:
In between, there is a splice where the C wire is ...
3
votes
2answers
336 views
Why does the pilot light go out when the furnace is running?
Every time the furnace fires up, it blows out the pilot light. Sometimes it will run a full cycle and blow out when it shuts down, and sometimes it will blow out about a minute into the cycle.
We ...
2
votes
1answer
89 views
What is the cost of one percent efficiency on an oil heater?
We've now had about 7 contractors come to our house and give us estimates for replacing a) our oil heater (system from the early 1980's, estimated at around 65% effeciency), and b) our central air ...
2
votes
3answers
2k views
Why is my furnace blower noisy when it starts?
The blower of my furnace makes a loud noise every time it starts. I understand that a large fan and the movement of large amounts of air will produce some noise. What I am puzzled by is the noise that ...
2
votes
2answers
131 views
How much current should I expect this motor to draw when it's running steadily?
This fan lists its "Max. Amperage" as 3.2. I assume the motor draws that much when it's first turning on, then settles down to some lower current. How much current should I expect it to draw when ...
2
votes
2answers
790 views
$400 electric bill traced to heater - what could be wrong with it?
Back in December/January, we got a real shocker; a $400+ electric bill. I thought there must be a billing error, so I went out to the meter, and found that not only was the number probably right, we'd ...
