RUDD Furnace cycling too often on heat cycle

[centsless]

Hello everyone, i'm posting this question in hopes of getting some insight to a problem that i currently have with my furnace

The problem:
I had a RUDD Silouette II Downflow furnace (about 10 years old). Here is what happens on a typical morning.

Thermostat is set at 62 at night and calls for 68 at 8:00 AM.
When the time strikes, the furnace kicks on with no problem, runs one cycle but not two seconds pass before it starts the cycle again. Now, we know that we are looking at a 6 degree jump, but here is my question.

1. Is it common for the furnace to cycle so often until it reaches its desired temperature? I know most other furnaces have a pause between and i'm concerned that this will overload the furnace. Especially since its runs constantly.

2. Is it possible for have the unit run longer in the hopes of having more heat output that way we can reduce the number of cycles until we reach the desired point?


Any thoughts would certainly be appreciated,

Thanks,

[davefr]

Yes, a system will cycle more frequently when it's undergoing a large change in the temp. It'll come on and get the home's air from 62 to 68 but the entire mass of the home is probably still at 62 degrees so the air temp will back off from 68 very quickly. This cycling rate will die down as the inner mass of the home also warms up to 68.

HP systems generally have a countdown timer to prevent restarts at <5 minutes but I don't know about your system.

A decent thermostat will do exactly what you want. The Honeywell Presite will allow you to set the max. cycles per hour of every stage of heating. It will also allow you to program the min. interval of off time to prevent short cycling.

You say you've had the system for 10 years. Has anything changed as to it's performance? If so then maybe a tech. should take a look.

[Irishmist]

centsless: I am gathering from your post that your system is gas fired and not a heat pump. Heat pumps use "intelligent recovery" so that the auxiliary electric heat is not brought on when coming out of a set-back mode. It allows a more efficient recovery than first-generation heat pumps that simply brought on the auxiliary heat to make up the difference.

In your case if it is a gas furnace, the short cycling does not make sense. A fossil fuel furnace is most efficient when running a more continuous cycle. If your set back is 62 degrees and your recovery setting is 68 degrees then the furnace should run until it reaches that setting (at least within 5 feet of the thermostat). Keep in mind that the thermostat will dictate bringing on the furnace and it 'reads' the temperature within about a 5 foot radius of the thermostat.

If there is a restriction in the airflow, i.e. ductwork, filter, etc. it could be causing the short cycling. If the duct work itself is restrictive, it could be causing the short cycling. I also agree that a professional should troubleshoot the system and provide you with their recommendations.

At the very least, what you are experiencing will shorten the life span of the equipment as well as have a severe adverse affect on the efficiency of the system. On top of that your overall comfort is diminished.

All the best, Irish

[centsless]

thanks guys,

and for the responses.

1. the unit is 10 years old, but i just recently bought this house (about 2 months) ago.

2. the thermostat is not in a location where it would severly be effected by the changing air temperature.

3. the thermostat (Lux 1500 LE) programmable has a feature where you can change it from 2 min to 5 min delay, but the manual itself states that this funtion is only applicable to the 'cooling' cycle. I guess if it was capable of doing it in the heating cycle, then that should solve the problem. but that's not the case.

So, i'm back to square one, and have been doing my research. A couple more questions in that respect,

1. Has the limit switch to do with any of this? i've heard that is its not clean, it can cause all sorts of problems related to this.

2. Is there a setting (i've seen dip switches) that could alter the duration of the burners/fan? I'm sure there are other factors to go with this.

davefr: the cycle rate does not slow down until it reaches the desired set point, after which it will cycle as normal (when it needs to and the internal air temp drops).

Thanks,

[Twilly]

Twilli says call your local HVAC company this should be an easy fix

[t527ed]

what type of filter and when replaced last?

[davefr]

thanks guys,

davefr: the cycle rate does not slow down until it reaches the desired set point, after which it will cycle as normal (when it needs to and the internal air temp drops).

Thanks,

Are you saying that it's cycling on it's way up from 62 to 68 but before it reaches 68 for the first time? And if so, are you determining the home's temp. directly from the thermostat itself?

If so, it doesn't sound right and you better have it looked at.

P.S. Feedback on Lux thermostats isn't too good here.

[centsless]

P.S. Feedback on Lux thermostats isn't too good here.

This is exactly what i'm leaning towards too. For a few reasons,

The previous owners lived there for 14 years (HVAC is 10 years old) and looks like they had a thermostat that functioned well for a long time. When i moved in two months ago, i immideately replaced it with a Lux programmable one and now i'm thinking if they had this problem (cycling issue) all this time, the unit (or its components) would have failed a long time ago. (which is not evident in the service history log, assumings its accurate).

So, then..

i'd like to get suggestions for a good/reliable digital thermostat (multi-day programmable).

Thanks much!

[pd07]

Look at the Honeywell 8000 series. Or the Honeywell Prestige series.

[BaldLoonie]

Shutting down on limit. That's why the boys are asking you about filter. If filter is new, try running one morning with no filter. If it stays running, you probably have an undersized filter or one too restrictive. May have to use just a cheapo fiberglass if that's the case. If running without filter still causes the short cycling, get a pro out to check airflow. Running hot isn't efficient plus those limits like to stick open leaving you without heat.

[davefr]

Look at the Honeywell 8000 series. Or the Honeywell Prestige series.

I just bought a Honeywell Prestige. It's a wonderful system. It's hardwired to the equipment and wireless to the remote OD sensor.

The normal user interface is very intuitive. Honeywell must have spent a lot of time making it so intuitive. Anyone could walk up and program this thing.

The advanced programming menu has wonderful options and each one comes with a complete help menu. You can control lockouts, cycles, delay time, and nag screens such as the filter change reminder based on run time days vs. calender days. (anyone have a good setting for run time days until next filter change using std. filter media??)

I don't know why homeowners spend big bucks on HVAC equipment but use a low end Home Crapo thermostat. The thermostat is the brains of your system and can save you it's cost. Use a good one.

[centsless]

Shutting down on limit. That's why the boys are asking you about filter. If filter is new, try running one morning with no filter. If it stays running, you probably have an undersized filter or one too restrictive. May have to use just a cheapo fiberglass if that's the case. If running without filter still causes the short cycling, get a pro out to check airflow. Running hot isn't efficient plus those limits like to stick open leaving you without heat.

Thanks for the tip, i'll run it without one and see if i notice a difference. Is there certain brands that are 'less restrictive' (depending on the material being used?)

Thanks!

[pfeifer]

hitting limit is usually caused from a very common problem and it sounds like you should call in a pro. to overlook your system because this is damaging to your equipt.

[centsless]

hitting limit is usually caused from a very common problem and it sounds like you should call in a pro. to overlook your system because this is damaging to your equipt.

Thanks, that's what i'll end up doing since i tried a few things last night from this forum. (removing the filter, cleaning the flame sensor etc) I even changed the thermostat to the old one that was installed, same issue.

[dlevu]

centsless : I have the exact same issue, did you get it resolved? can you let us know how?

Thanks.

[Special-K]

centsless : I have the exact same issue, did you get it resolved? can you let us know how?

Thanks.

This is a two year old thread, Op is likely not around to answer.

You would be better advised to start a new thread if you wish.

Thread closed.