How to make sense of the choices? Thread split off.

[syndicated]

You are giving advice on and making comments on things you evidentely do not fully understand. That sort of thing may be ok on the DIY sites you are on, but that sort of thing is not acceptable on a site where there are so many professionals in the HVAC industry who have to correct your misinformation.

When a furnace overheats, several things happen, depending on the model of the furnace. At the very least, more than just shutting off the gas valve occurs.

It doesn't matter what type of thermostat is installed on any furnace dependent on the thermostat to initiate furnace operation. All any such thermostat is is an on/off switch that is thermally controlled.

We all stand in awe of your superior intellect.

[54regcab]

RoBoTeq it doesn't really matter how I answer your questions, you have personal issues with being 100% right 100% of the time. Even in the 10 + 13 = 8 SEER, 2nd Amendment, and Abortion discussions you're the same way. Quick to attack anybody who doesn't 100% agree with you, then go insulting them. Even when somebody DOES agree with you, you still find something to insult them about. Great professionalism shown there, you must be a real pleasure to work with...

Oddly I agree with a lot of your posts on Social & Government issues..

[RoBoTeq]

We all stand in awe of your superior intellect.

As well you should....

[RoBoTeq]

RoBoTeq it doesn't really matter how I answer your questions, you have personal issues with being 100% right 100% of the time. Even in the 10 + 13 = 8 SEER, 2nd Amendment, and Abortion discussions you're the same way. Quick to attack anybody who doesn't 100% agree with you, then go insulting them. Even when somebody DOES agree with you, you still find something to insult them about. Great professionalism shown there, you must be a real pleasure to work with...

Oddly I agree with a lot of your posts on Social & Government issues..

So now you're a professional analyst, too?

I only have issues with those who make commentaries that are wrong about HVAC issues, and you do just that....a lot. The information that you post is never supported by any facts, just your rantings that HVAC professionals don't know how to install proper sized furnaces....blah, blah..

You have refused to respond to several specific questions I have posed to you to support comments you have made. I realize that you don't respond because you don't understand what you are posting about, yet you continue to make erroneous posts. Why are you trying to impress those of us who are professionals in the HVAC industry? Isn't it bad enough that you are giving DIYers irresponsible information on DIY sites?

Don't get me wrong, I'd love to banter with you about thermostat controls, the only thing you seem to really be involved with in the HVAC industry. But please, stop making erroneous posts about furnace oversizing and furnace internal controls. You really do not understand what you are posting about.

[54regcab]

What other DIY sites are you talking about that I'm supposedly insulting the HVAC profession? Please let me know what they hell is going on, because I have no idea what you are talking about.

When I supported the power being disconnected from the thermostat by posting a schematic, you insult me without giving any explanation of why the schematic wasn't relevant. Do you not believe that any furnaces disconnect the power to the thermostat when they reach high limit?

[Mr Bill]

.Do you not believe that any furnaces disconnect the power to the thermostat when they reach high limit?

There were a lot of your earlier model furnaces prior to the 90's, that were the old draft box/hood style that the high limit did "depending on the fan limit" shut the high power leg to the furnace, but most were wired to open the low voltage. I have not really looked at the schematic you posted, but with 99.99% of all the newer furnaces, if the power were taken out with a open high limit, how would we be able to read the trouble codes when the tech arrived? I will say this. I have yet to run across any newer furnace that, unless the breaker was tripped, or maybe a bad low voltage transformer or door switch, that the board was not still active in the circuit upon arrival. I can't get into it on this forum, but trust me if your stat only needs 24v to keep it active, I could personally wire it using the same furnace transformer, to were unless the low voltage transformer was fried, it would stay powered regardless of the limits or the board being out.

[54regcab]

MrBill, the 24V is cut to the board terminals going to the thermostat but not the boards internal CPU. The error codes work, even though there is no 24V going to the thermostat. Look close at the schematic, it's a thin "wire" from the 24V to the CPU before sending the 24V to the limit controls.

We could wire straight to the transformer to keep 24V at all times, but won't do so. If the furnace is hitting high limit they need to call their HVAC company and have them correct what's causing the problem. We'll check the air filters to see if they are dirty or the highly restrictive type, but if it's not that we let their HVAC company deal with it. Poor ductwork is to blame for a lot of the high limit problems, clogged blower wheels and a-coils account for some of them also.

[Mr Bill]

We could wire straight to the transformer to keep 24V at all times, but won't do so. If the furnace is hitting high limit they need to call their HVAC company and have them correct what's causing the problem.

I could take that same board, add a simple N/O relay between the red stat wire on the board and the stat, so when the limit opens, the red wire from the stat to the board, is open, but the thermostat is still powered up. There is no more risk involved, than you adding your thermostat, this is the understanding of simple controls not rocket science.

[RoBoTeq]

What other DIY sites are you talking about that I'm supposedly insulting the HVAC profession? Please let me know what they hell is going on, because I have no idea what you are talking about.

When I supported the power being disconnected from the thermostat by posting a schematic, you insult me without giving any explanation of why the schematic wasn't relevant. Do you not believe that any furnaces disconnect the power to the thermostat when they reach high limit?

If you don't know what sites you post on, I have no desire to refresh your memory. You even posted one of those sites on a thread on this site.

You were wrong about the power to the thermostat being cut off when a furnace goes out on high limit. There is nothing in any furnace that turns off power to the thermostat due to a limit switch opening. My stating you are ignorant of furnace functions should be taken as positive criticism and not as an insult. The only thing insulting is posting things that are not accurate.

[Mr Bill]

Also if you look closely to your schematic you posted, the "W" wire to the gas valve has it's own limit, between the "W" on the board and the valve.

[RoBoTeq]

Also if you look closely to your schematic you posted, the "W" wire to the gas valve has it's own limit, between the "W" on the board and the valve.

He's misreading the schematic. According to what reg is stating, the gas valve would be constantly energized.

[Mr Bill]

40-60K should be good for 2500sqft, have a load calculation done.

Would this setup work well with this much sq. ft. International Falls, Minnesota?

[54regcab]

I could take that same board, add a simple N/O relay between the red stat wire on the board and the stat, so when the limit opens, the red wire from the stat to the board, is open, but the thermostat is still powered up. There is no more risk involved, than you adding your thermostat, this is the understanding of simple controls not rocket science.

The issues is not wiring in a way to keep the thermostat powered up, it's getting the furnace situation corrected since it's not operating properly. We don't want to "hide the problem" by wiring in a control circuit. It makes me wonder how many systems out there with battery powered thermostats are hitting the limit and the customer doesn't even realize it.