When is the last time the air filter was changed. may also have a dirty indoor coil.

 

Thanks for the prompt reply! We moved in here mid June or July, so possibly around that time, but given we had no working smoke detectors when we moved in, I wouldn't be surprised if it was long before that as I am getting the impression they perform no routine maintenance here.

One thing I was unclear about, but would like additional feedback on the notion that the furnace can heat our unit with out actually putting out warm air. I have no knowledge of HVAC at all, and will not pretend to. However, it seems like basic logic that the furnace has to put out warm air to keep the unit at the set temperature. Logic aside, the furnace *is* keeping our unit heated properly even when we had a ~5MM gap in one of our windows letting cold air in.

 

I believe you have a heat pump. Older ones don't put out real warm air. if its just straight electric resistant heat, it may be a smaller strip heater, and the air won't feel real warm.

 

Thanks for the info beenthere. I like your avatar, even though I am more of a fan of the current Ford and Dodge US cop cars.

clogged filters, dirty coils, undersize unit, the hissing is probably from leaking duct work.

In regards to the hissing, for what it is worth, the first week or two(maybe longer) we were running the furnace, it did not make this hissing noise. When I tried to tell the property manager this she just started huffing and puffing and insisting nothing was wrong even though she could not explain why the hissing started suddenly.

 

clogged filters, dirty coils, undersize unit, the hissing is probably from leaking duct work.

 

do you know how to change the filter??? if you do, a new one is $1.50, throw a new one in and see what it sounds like?

btw, is this hissing sound constant or just when the blower runs? Is it a hissing sound or more like a Buzzing sound?

 

Here is a pic of the filter, I couldn't really tell if it was dirty or not.
http://i.imgur.com/DEDx4.jpg

As for the hissing, neither. Another reason I compare it to air brakes on a semi is it only happens for a few seconds right before the furnace is about to shut off.

 

Not dirty enough to cuase a problem.

Its also possible you have straight A/C with electric heat. And the A/C is coming on with the heat is on.

 

Well a little update here, the hissing happened at least twice last night, but the furnace did not shut off right afterwards. It just kept on running. Now for what it's worth, last night was probably the coldest night here so far this year getting down in the mid to upper 20s. Because of this I think we had our thermostat set a bit higher then usual.

One other thing I forgot to mention, the other day I had played with the thermostat a bit. I noticed if I suddenly turn up the temperature on the thermostat to a dynamic degree, say around 7*F(it's an old analog(?) thermostat with a slider - so I am guessing here) it does put out a more noticeable amount of warm air.

The later paragraph is making me think it is indeed refrigerant in the evaporator coils based on the information you guys have provided.

 

You have a heat pump with electric resistance back up heat. When you turn the tstat setting up ~2-3F above inside temp the resistance heat comes on to catch up to the new set point so the air is warmer, when it gets to the same temp just the heat pump runs and the air doesn't feel as warm. The hissing noise is a defrost cycle to remove any built up frost or ice from the outdoor units heat transfer coil. In defrost the unit switches from heat mode to cool mode and the resistance heat comes on to temper the cooled air so it doesn't blow really cold air. Maybe the resistance heat is not coming on in defrost thus blowing cool air into the home while in defrost mode. The hissing sound is a normal noise for a heat pump in defrost. Heat pumps only blow out ~90F air when the resistance heat is not on so it does not "feel" very warm but does heat the house. Hope this explanation helps.

 

jt, if you don't mind me calling you that, this went over my head a bit here, but I think I got the basics. However, the defrost part has me a bit confused, because:
1. The noise was not there for the first week or two of running the furnace.
2. Maybe this is irrelevant but generally it has not been cold enough to worry about freezing.

Buy a Thermometer and tell us what temps you are getting out of your register's. What type of heating did you have in your OLD house before this one?

JT ^^^^^ Nailed it. Thats what I was thinking. I also don't think you are used to this style of heating

Buy a thermometer and place it in the house here and compare it to the thermometer portion of the thermostat unit?

As for the old house, not sure. It was a small 550 sq foot one bedroom apartment. For what it was worth, the unit was located in the bathroom ceiling. However, the furnace filter, which maintenance replaced one or twice a year no matter what, was located just outside the bathroom in what appeared to be a large heating vent the size of say a vent you would see in a drop ceiling in a business.This is not a house either. It is a rental property with 4 or 5 buildings. Each building contains four town house units.


Let me add that just as I type this it did the hissing noise for a few seconds. This time the furnace had been on for maybe 1 minute. I waited to see if it would shut off, but it didn't. Then a few minuets after this, it did it again for about 3 seconds. Then maybe 2 or 3 minuets after the second hiss it shut off.

The reason I have been so persistent is because of the alarming rate of issues I am having with property management. We had about a 5MM gap in between the top and bottom window in our living room allowing wind and bugs in. It took a week to be "fixed" with weather stripping tape and duct tape on the inside and outside. Same for windows in our enclosed unfinished balcony/"storage area" that leaked "when the wind blows just right." One maintenance man has done a no call no show. We had no working smoke detectors in our unit, and I found that when I removed the upstairs smoke detector from the ceiling, I found a live exposed coper wire hanging loose. After the first maintenance man no called no showed, she claimed the second one had an "emergency" when he was scheduled to come out. And this one has me alarmed, we had a pizza delivered the other night. My girlfriend got the door for a change and the guy was telling us that he was almost our neighbor but found a ton of mold in the unit and the property manager claimed they would not do anything about it. Oh and the maintenance supervisor(?), went out of town, left no one capable of fulfilling his duties, and gave an estimated return date of late one week or early the next. If you have taken the time to read this slightly incoherent quick rant, you can understand why I am not taking the property manager's word that there is nothing wrong.

 

Buy a Thermometer and tell us what temps you are getting out of your register's. What type of heating did you have in your OLD house before this one?

JT ^^^^^ Nailed it. Thats what I was thinking. I also don't think you are used to this style of heating

 

It probably wasn't cold enough outside for the unit to run long enough to force a defrost mode the first few weeks you ran it. Buy a thermometer and track the temp, in heat pump mode it will be ~90F in heat pump with resistance on it will be ~100-115F and in defrost it will be ~75F (should only be this temp for a few minutes, around the time you hear the hissing noise) if it blows below the temp in your house at any point you have a problem.

 

Buy a thermometer and track the temp,

The temp of the heat pump? I think I am getting in over my head now..

 

The temp of the air coming out of vents

 

Ah ok. I can pick one up tonight on the way home.

FYI, we got our electric bill today. It did jump ~$14 from last month, but I think this is in the realm of normal. I don't think this would have been the best month to judge though, because the temperature has fluctuated to much here in the Southern Indiana tip. A few days ago it was nearly 70*F(high), and today's high toped out just under 40*F so we have actually had to jump back and forth between our heat and AC, and some days we can just leave the heat/ac off with out even having to open a window.

I think this coming bill, and a thermometer will be the real testament though. Technically the maintenance supervisor could have just picked up the dang phone and explained this to me, but I guess that is to much work. So thank you guys for all the help, and putting my mind at ease, well to some extent, on how this HVAC system works, and being able to provide real evidence to the property manager if the HVAC system is indeed malfunctioning.

 

Been a few days and wanted to update this so I hope a double post is fine.

Our maintenance man finally came out. He still did not actually look at the furnace, but did confirm that it was a heat pump model. He said the noise was the freon(or something) shooting out of the furnace to the AC unit next to the building, or something along that line. He also said it was normal for it to work really hard, and put out what seems like cold/cool air. Of course I guess you guys know all that already.

Grabbed a <$1 thermometer from Walmart, popped out the vent in the living room, put it just under the register, then put the vent back on. I checked it a few times over the course of a few days and at random times. It was always reading at about 75*F. When I checked it, the air was not running but, I am unsure how long it had been running for previously, or how long it had been since the air had been running.

It is still making the hissing noise all the time, and it is doing it in temps as warm as ~50*F outside.