Hi,

I purchased a home about a month ago and have noticed that the heating is a bit different than what I am used to.

In my previous home, there was a heat pump that ran until it got too hold and then the electrical strips came.

In this case, I have no reason to believe that there is a heat pump of any type at all.

I am not familiar with propane being used in this manner.

So there is a Thermostat installed with some HVAC companies name on it.

Reminds me of my old Honeywell TH5220D...probably is!

https://www.google.com/search?q=th52...hrome&ie=UTF-8

When it gets cold, I notice that hot air comes from the vent for a while and then starts to go cold.

I then notice that the heating system does not reach 70 degrees and can drop as low as around 67 degrees.

Then hot air starts coming through the vents again even when it is pretty cold outside and it is capable of reaching the set 70 degrees.

The fan is set to auto.

It seems almost like there is a second thermostat in the system somewhere.

I guess this is considered a "furnace" or something like that. Not familiar with this setup.

There is a heat pump outside but that looks like it's only for the A/C.

I believe that this is a York furnace. There is a bunch of stuff in my crawl space that I don't understand but I am willing to investigate further. I just don't know where to start.

Thanks!

 

The outside unit is called a condenser. You can't tell by looking at it if it's a heat pump.
If it was a heat pump it would be running in the cold.

It sounds like you have a propane gas furnace with a split A/C system.
By the way your furnace is cycling.... it would appear that it may be overheating and shutting down on high heat. Your first step is to make sure the filter(s) on the furnace are clean. The filter could be behind a wall vent or at the furnace.

 

Right, the outside unit (condenser) was not running in the cold at all. Thanks for clearing that up.

I have located 3 different fiberglass filters in the home. I didn't know what each one did so based on previous experiences and advice from this board over time, I replaced them with Merv 6 pleats. Two filters were 20x20x1 in size. They were both found in my living room. They were both on the same wall. One was about a foot of the ground and another was about 6 feet off the ground. On the other side of the wall in the same room there was a larger 20x25x1 filter.

Might the system use different filters for heating and cooling?

Might there be an additional filter somewhere in the system where the "heating unit" is installed in my crawl space that could be dirty?

The crawl space is reasonably easy to investigate, I just don't know what is going on down there because there seems to be more than one piece of equipment.

Thank you!

 

There may be another in the crawlspace. You'd have to check.
Typically there is only a single filter as too many filters will restrict airflow.

 

Thanks, I will poke around the crawl space and come back. I'll try to get a list of the equipment that I am seeing and then post back. Not even sure what I am looking at unfortunately.

 

Before stepping into the unknown, you did mention that such a system usually has just one filter. As I mentioned, we are already up to 3.

Do those 3 filters potentially already serve as "the" filter?

Any reason what purposes these described filters might serve?

Model numbers and info to come but just checking first.

Thanks again.

Above questions still stand but while waiting for an answer, I entered the crawl space and this was the only model number that I could find for anything besides a bunch of duct work. The model number is not very google friendly. There is also a red light flashing on a circuit board inside as you can see.

 

We had a house in CA (gas) that had centralized return ducts (one upstairs one downstairs) that contained filters with a third at the furnace so not too unusual!

 

Thanks, well all 3 filters enter the same metal ductwork FYI.

I got the model number wrong, it is actually: TG8S060A12MP11B

Thermostat is as I suspected TH5220D. Pulling it out of the wall to check the wiring immediately made hot air come out of the vents upon returning it to the wall.

Any ideas?

Thanks

 

So I went down to the crawl space with an HVAC guy who is a friend of a friend. He showed me that when the pilot goes out all I need to do is hit a light switch to see if the pilot stays on.

We observed a light flashing 7 times. He took a measure of some motor and believes it to be slightly out of spec where spec is supposed to be .5 or .05 or .005 etc. and the reading is .6 .06 or .006 etc.

He also mentioned that some metal ducting going into the unit was experiencing drafts from the outside. The ducting lead to the roof and he mentioned that the cap was still on and that everything looked alright.

Poking around here there seem to be quite a few posts with the 7 flashing lights.

While waiting on the HVAC guy I'd like to know if anyone has any additional ideas.

Thanks.

 

So 800 bucks later, the HVAC guy cannot figure out what is going on. All filters have been identified. Flame sensor has been cleaned, Inducer Motor replaced, some switch, and the control board has been replaced.

It cycles up to 3 times and then blows cold air for an hour. Replacing the board just made the blowing the cold air last about 1 minute....obviously a firmware update.

This is definitely a York Furnace.

Help!

 

Removing and reconnecting the thermostat clears the fault.
Almost the same thing as powering down the furnace and then repowering it up.

It sounds like your tech is a parts changer. If he doesn't know how the furnace is supposed to work.... changing parts won't help.

Does the furnace run fine until he's not there or does it fail when he's there and he can't figure out why ?

You mentioned pilot light. If your furnace has a pilot light it's probably an intermittent ignition system. That can be a problem area if the pilot doesn't operate correctly.

 

You need a new tech, desperately.
I haven’t a clue why you were told anything about a pilot light because your furnace has no pilot light. No such thing exists on your furnace.
An error of 7 red flashes should be an ignition lockout.
Has this guy checked mA from the flame sensor? Gas pressure? Cleaned the burners? Checked the propane regulator?

 

He has checked the propane regulator where it feeds the house. He has replaced the pressure switches and the inducer motor along with the control board. Replacement of the control board resulted in the only noticeable change. Lockout lasts about 20 seconds instead of 1 hour now. This leads me to believe that these systems are so problematic that the manufacturer changed the lockout time so that the system can keep trying after it fails.

He did take measurements but at the time I can not be sure of what exactly. He mentioned that his measurements lead him to believe that the inducer motor was weak and he replaced it accordingly.

Ignore the part about the pilot light. I probably got used to using such terms with my portable heaters.

The problem *ALWAYS* starts after he leaves.

Of note, I notice that there is some "short hand" when discussing units of this type on the internet like "8 series" that everyone seems to know and be comfortable with except for me. Does anyone know what "series" this is so that I can go ahead and do some deeper dive googling?

Also of note, I found another sensor at the top burner that is flat in shape. What is this called? It had white stains all over it. I sanded it but it was embedded into the sensor. It is not the same as the cylinder shaped flame sensor in the lower burner.

I'd also like to begin to troubleshoot this unit myself. Do you have any suggestions? I was an electronics bench tech in another lifetime so that should be helpful with some troubleshooting I'd think.

Thanks.

 

That is a York series furnace. Group TG8S. Manual below.

York TG8S manual (pdf)

 

Thanks so far. Manual is a great start.

 

The manual does not have a parts list which includes part numbers.

Is there a way to get that parts list with part numbers?

Also, the manual does not show the below part from what I can see.

What is this part called and should it have this white area on it? Is this the ignitor? Is it also referred to as the "hot air ignitor"?

 

The pictured part is the ignitor, more specificly, hot surface ignitor. That partcular one appears to be made of silicon nitride (lucky for you). Had it been silicon carbide, it would hve broken when you used sandpaper. The white is not unusual.

 

Most service manuals for furnaces don't have part numbers in them.
Part number listing for TG8S furnace

That igniter is OEM part # S1-02545231000. That is the one part that it is advised to have a spare of. They can crap out at the drop of a dime. You can search using that part number.