High efficiency furnace(s)&multi speed blowers

[Aage]

Thanks very much for the update, Hank. I guess that this is a new model for the Atwood folks, so thank goodness they have engineers that care if it works.

Too bad they are using the clients to debug it though. Someone there must have trained at Microsoft!

Looking forward to hearing about how things work out in your March trip to them. Sorry, I don't know where SLC is...?

[hshovic]

SLC = Salt Lake City

[Aage]

Originally Posted by hshovic

slc = salt lake city

10q!

[wmarsha]

okay guys, you have whetted my appetite for more info-has hank made it to SLC yet? I know, I know it is only 3/9, but my philips screw driver drill twitches everytime I get close to the old furnace....any other news?
I used a small electric heater at Ft Stevens in Or this past weekend-no troubles. but I know that noisy furnace is there, and one look into the compartment told me it needs cleaning very much so! I hate to yard that thing out without knowing a good replacement is on the horizon! Thanks Hank.
bill

[hshovic]

Not wanting to overburden with data, I was going to update next week. But due to the overwhelming interest

I have an appt. next Tuesday at 0800 at the Salt Lake Atwood Engineering facility (small blue building with no secretary) to review the problem with Chris Schmidt and other engineers. Not without effort, I might add. I stay at the Temple Square KOA, but have to make the trip to Salt Lake in 10 hours on Monday . And have to cross SLC traffic at peak of the rush hour. Oohboy. However, then heading to Death Valley flowers and Arches N. P. with a (hopefully) quiet furnace.

[hshovic]

On Tuesday I had a very cordial appointment with Chris Schmidt, an engineer with Atwood mobile products. He took the whole thing apart, replaced a blower wheel,
which made a slight difference in the hum. He also aligned the motor. But not much
difference. He finally said he thinks it is normal and is a result of the design of the "chopper" that reduces the voltage for the slow speed. We discussed putting more insulation, but there is no room. He has no other suggestions other than to return it.
And neither do I. The hum is slightly better, but still there and still has the occasional
"beat" note which is irritating. So hopefully this helps. I am not sure what to do other than give up. I can use the high only speed and it is a bit quieter than my old furnace,
but then it is 3000 Btu smaller in size, but still heats up just fine. Seems like not much for the $600 it cost.

[Aage]

Thanks for your comments on the meeting, Hank. Somewhat disappointing to hear that you are still not able to take advantage of this seemingly breakthourgh technology.

A couple of questions:

Do you think that it could be that this issue is endemic to this model installed in your 25-footer? I'm wondering if it would do the same thing in my 33 year older 31-footer.

Not a fair question, I suppose, but if you still have a means to contact the Atwood engineer, perhaps you could ask him if he has heard of other complaints from XT users, or is yours an isolated case?

Also, in terms of the insulation question, did anyone talk of the type of sound insulation matting that is used in automobiles by aftermarket sound installers to deaden structural panels in automobiles? It is fairly thin, much thinner than say fibreglass panels. I wonder if there is enough space for this type of treatment in your TT...?

Regards,
Aage

[wmarsha]

I was hoping for Hank that Utah would have held the magic answer...I am frustrated by the current answer. I want to eliminate the noise of my existing unit, but don't want to trade X for Y noise, if not necessary. Thanks to Hank for his reporting. I would like for others with XT experience to chime in as well as hear answers to the ques above. Sorry, Hank but you are the guinea pig on this deal. Have a safe enjoyable trip...
bill

[hshovic]

I am not happy with the response. I don't recommend this unit! I have it only on the HI setting now and it is no worse than my old unit. You can still hear the chopper but it is covered by the blower noise. What a waste of $900.

Aage, I don't have the answers to these questions. My next call is to a manager to inform him of my problem and the non-solution. I will have to tell him the 25,000 Airstreamers now know the unit is NOT good for Airstreams. Maybe it is good for giant 5th wheels that have a lot of distance between the unit and their living spaces.

[dufferin]

have you tried silent block where the furnace sit on the floor? I know that in the new AS the floor act as a sounding system and can amplify any vibrating noise.

[hshovic]

Originally Posted by dufferin

have you tried silent block where the furnace sit on the floor? I know that in the new AS the floor act as a sounding system and can amplify any vibrating noise.

The noise is definitely electromechanical, but taking the furnace out to try that might be problematic. It is stuck in there real tight. Thanks for the suggestion!

[Aage]

Originally Posted by hshovic

It is stuck in there real tight. Thanks for the suggestion!

Hmmm... No chance that the tight installation could have stressed something and caused the noise is there?

[wmarsha]

Okay, I re-read the entire thread, and although somewhat disappointed in what I thought was going to be my replacement furnace (Excaliber XT), I am still considering purchasing one of them. My thinking:
1) we now know at least the possibility of a humming exists.
2) we still do not know completely what is causing the hum-it may be (no slam intended Hank, but you said your install was tight) the installation itself. Or lack of insulation, or vibration isolation.
3) This unit has imho the right ideas of lower BTU ratings, lower blower speed, AND a dual blower speed with dual burner operation.
4) Assuming the folks Hank dealt with are similar in mental make-up as myself, then perhaps they will continue attempts at correcting this problem.
5) Knowing 1-4 above, once such a unit is purchased by yours truly, I would (will) bench test it to see (hear) if the hum is present.

Now having said all this, my wallet is recovering from the purchase of new tires for the AS AND for the wife's get around-mobile, so do not hold your breath waiting for my report. I WILL pull the orig furnace soon and bench test it, using a sound pressure meter to determine actual noise levels. In fact, I will go out there right now, turn on the furnace and measure the sound levels at two repeatable places within my AS and log that data for future reference. Then, in the warm weather in between trips, I will purchase an XT unit and as stated do the bench test.

The bench test will either a) reveal the hum, or b) reveal no hum-hopefully no new empirical noises. If a), then I will seek to isolate the hum and eliminate or at least abate it. If b) then I will report that, and monitor the install very closely, to be sure I do not wrack the frame of the new unit, or cause it to rub anywhere that would amplify unit sounds.

So there is my March report-I sincerely hope that Death Valley has treated Hank well, and I sincerely hope that he has happier resolution to the hum in the very near future. I think I speak for everyone following this thread that Hank's openness has been welcome. Thanks again Hank.
Keep us posted if there is any change in the hum-perhaps you can tune it such that it will be a lullabye tune!
be cool
ol' bill

[wmarsha]

okay, using a Simpson 886-2 type 2 sound level meter on the A scale, set to the 50 db meter scale, the following measurements were made:
3/29/2010 1985 31' excella with orig furnace

On startup, old Betsy did her thing-sounded like a rusty wheel factory and squealed quite loudly-a full 62 db!

Once it settled in it read: 51db constant at 2 feet AFF, 90 degrees to unit, 6 feet from the duct register which is located very near the furnace up front.

In the back bedroom, at 3 feet AFF, 6 ft from duct register 45 degrees from the register face, the unit produced 42.5 db constant.

Now, don't get too excited, these will only be relative db figures in my AS. change any of the parameters of the test and you will get differing data. But as I publish the data it should give us some RELATIVE figures to work from.

Once a new furnace is purchased, I will again make these measurements in the same place. My money is on the following: the experiement will result in very nearly identical sound levels-only my wallet will know the difference.

[hshovic]

Thanks to all you are interested.
I have kept the furnace on "high", but have seldom used it in the Mojave.
However, now that I am back in Utah, I am hearing it again.

Bill,
Nice ideas. All possible.
Extra data: There is a sleeve around the motor. It is secured by a pipe clamp.
Loosening the pipe clamp changes the humming sound. This also points to some stress
possible in the structure.

My next step today is to call Atwood and request a new furnace, installed
when I get back home.

[hshovic]

Latest:

Atwood has agreed to replace the entire unit when I get home.
I will check on the vent comment, and on the idea of some insulation. I will also try to have it bench-tested before installation.

If it's still noisy, at least I got their attention. Engineers and managers had to get involved, so
since $$ talks, it might make a better furnace eventually.

[wmarsha]

Hi Hank, any news on the furnace replacement front? My old unit is sitting under my work bench just waiting to be: 1) replaced by a new unit 2) re-installed with a new motor. Have you completed the trek home yet?
thanks for indulging me (us).
bill

[hshovic]

Bill,
I have an appt next week at the local RV repair place. They have a new furnace. At the least, I will have cost the company some $$ which of course is the only way to make any changes. At the most, I will have hum-free living. Will post with results.

[Aage]

I tell ya, I have my fingers corssed over here, I want this new technology to work!

[hshovic]

And I did get a new furnace. It appears to be a design problem. It does the same noise at low speed. So that ends my saga. I give up. Maybe the cost of this to the company will start a design change...