[MiniMe4HVAC]

With a 67f temp rise you are only within 8f of max. Plenum limit switch could be getting to 210f due to radiant heat from the heat exchanger. Are the burners staying lit the whole hour your house is warming from 18c to 21.5c. A furnace tripping limit will allow he blower to run the whole time blowing warm air and the homeowner may not realize the burners are cycling. Watch it for 10-15 minutes and verify the burners do not shut off. Clock the gas meter to verify furnace is burning the correct amount of gas. In US measurements seconds for the 1cuft dial to turn divided by 3600 is your btu/hr in thousands. 3600/70k BTU = 51 seconds for the 1cuft dial to turn one revolution.

I am going to clock the meter this morning
I am now inspecting the AC coil

No the burners do not cycle anymore. There were at that point a while ago. Now they are fine.
They were short cycling but I fixed that by reducing the gas pressure. I am going to find out soon if the gas pressure was OK or not

 

[54regcab]

AC coils can "look clean" but be clogged deep inside the fins. Especially possible is somebody has recently "cleaned the coil" without pulling it. Static pressure test is the only way to know for sure.

Leave the gas pressure ALONE unless you have the proper equipment and expertise to set it correctly. You can easily cause more harm than good by setting it wrong. Clocking the meter is just a quick check to see if fuel consumption is close to spec, it does not verify correct gas pressure.

 

[MiniMe4HVAC]

AC coils can "look clean" but be clogged deep inside the fins. Especially possible is somebody has recently "cleaned the coil" without pulling it. Static pressure test is the only way to know for sure.

Leave the gas pressure ALONE unless you have the proper equipment and expertise to set it correctly. You can easily cause more harm than good by setting it wrong. Clocking the meter is just a quick check to see if fuel consumption is close to spec, it does not verify correct gas pressure.

Stay tuned I am going to post some scary **** soon

 

[timebuilder]

I'll give you this: you are one of the more skilled and comprehensive posters to come to the AOP forum.

Are you doing the CAD work at home, or on a server-based platform at work?

 

[MiniMe4HVAC]

Nope ...I learned CAD by myself and I am learning the basics about HVAC now. The renderings are made in Sketchup Pro, a light version of Autocad, user friendly...so I am not as smart as you believe
I am an IT guy but I attended an east european top university in my ex communist country and those bastards wanted to make an Einstein out of each one of us so I got into the habit to learn things by myself as I am doing it with my furnace right now.


BTW I got to access the AC coil and the secondary heat exchanger coil.
Man! ..

Here are the horror pictures

This is the AC coil

This is the Secondary heat exchanger coil

 

[MiniMe4HVAC]

So now it is clear that mu installer did not want to help me
The furnace is dirty and I have to clean it up.
What is the best way to clean these coils

I am thinking about vacuum first for a rough cleaning
Next I would use one of these if you guys are telling me that is right

and the last step would be to vacuum it again

 

[54regcab]

The coils don't look that bad considering thier age, I think your problem is elsewhere. What were the results of your gas meter clocking?

 

[rider77]

After that many years, I'd be pulling the coil and cleaning it.
Of course, if you don't plan on ever using the air conditioner again I'd just pull it now and close the duct back up.

 

[MiniMe4HVAC]

I am going to first clean this thing and after that I will deal with the gas pressure.
Cleaning this might allow me to go back to fully open gas valve on the main pipe and then I can assess the situation properly

 

[MiniMe4HVAC]

After that many years, I'd be pulling the coil and cleaning it.
Of course, if you don't plan on ever using the air conditioner again I'd just pull it now and close the duct back up.

I will have to learn about how I do that
I suspect there are some issues with handling the freon here
Otherwise it should not be a big deal since it can be removed. it looks like this

 

[MiniMe4HVAC]

So how do you guys recommend me to clean these coils ?

 

[rider77]

The refrigerant would have to be removed, lines cut and sheet metal cut to allow removal of the coil.
A strong non-acidic cleaner would be preferred along with something that could blow through the coil. There's just as much dirt inside the fins, if not more.

 

[beenthere]

This thread has been reported twice. Seems like a lot of DIY info. Above and beyond what is allowed.


Thread closed.