Defective? Elec Heat Air Handlers

[John Smith 2]

W

This is a very good question, forget about the airflow for a moment and check temp rise. This will at least tell you if there is enough air moving over the heat strips, I was told back in the early 70's by my instructor, before reinventing the wheel, check for the most basic things first. Please check this and get back.

Mr. Bill, thanks for your reply.... What would you think if I added this observation that we have found. About 75 per cent of the surface area of the heat strips are not in contact with the airflow passing from the blower ports through the heater compartment. To back this up where the air does make contact with the surface area of the elements there is no discoloration on the elements. The surface area out of the air flow is found to have turned a dark brown to black color. Please give me your thoughts on this. Thanks!

[Saturatedpsi]

W

Mr. Bill, thanks for your reply.... What would you think if I added this observation that we have found. About 75 per cent of the surface area of the heat strips are not in contact with the airflow passing from the blower ports through the heater compartment. To back this up where the air does make contact with the surface area of the elements there is no discoloration on the elements. The surface area out of the air flow is found to have turned a dark brown to black color. Please give me your thoughts on this. Thanks!

I've never seen anything (don't believe) like you describe...how 'bout taking a pic and post it up for us?

[Saturatedpsi]

Another question: is this equipment brand/model/design something that's been around a while or something out of China that you decided to try?

[Mr Bill]

Does this look like your elements?

[garyed]

I agree with the guys on checking the temperature rise. That should tell you everything you need to know. If I had that problem I would temporarily bypass all the limits long enough to do the test. It shouldn't take more than 15 minutes. For reference a 10kw strip at 800 cfms should give about a 40 deg. Temp rise. If you figure the CFM's by the temp. rise method then if your rise is too high you've got airflow problems & if its too low you've got air bypassing the strips. If its in the ballpark then I would think the limits are probably the problem & the factory reps recommendation is correct.

[John Smith 2]

Thanks Mr. Bill, Saturatedpsi and Gary for your replies... The units were sold to me by one of the largest (if not the largest) mfgr/distributors in the country, however, the units were manufactured by another company under another label. I don't want to yet mention their name because I don't want to bring upon them any bad press. I have bought hundreds if not thousands of fine air handlers and condensing units from them and probably will continue to do so. When you look at this unit from the outside and for the most part from the inside, it looks almost identical to the units manufactured here in the country by other big name brands. The one exception is the heat strips. The heat strip that you depicted is not what is in this unit we are having trouble with. The heat strip you depicted is in the brands that I replaced the troubled unit with. Notice how the strips you posted have thin curely cue wires stragically fashioned in size & shape and placed to be directly in front of the two blower ports. Every inch of these curely cue ht strips are washed in the air stream thus giving up all their heat to the supply air; unlike what is happening with the troubled units. I'm not sure the factory could up the safety temeratures after being tested and labeled, if they could I think they would have. Besides if the customer is not getting the benifit of all the heat being generated being brought out in the room and rather just heating up the furnice and ceiling cavity its really not fair to them for the wasted energy cost.

[Saturatedpsi]

I don't want to yet mention their name because I don't want to bring upon them any bad press.

I can respect that position. So getting back to your original question of whether or not anyone had experienced the same problem with the same units, the answer at this point seems to be, "no".

But it also seems I'm the only one satisfied with your evaluation that airflow isn't the problem. So unless you either jumper out the limits to obtain a heat rise value, or post a pic of the elements that might visually confirm your suspicions, I'm afraid the discussion is at a stalemate.

[alcomech]

How many stages of heat are there?
What is the resistance of each heat strip?
What is the voltage and phase for each stage of heat.
What is the actual current AMP draw or RLA on each individual heat stage when running compared to listed RLA.
What is the rating for limits or better what is the part number.

With this info it can be easily determined what the minimum required air flow should be and also what your temperature rise will be.




Troubleshooting is not part of the repair............understand the symptoms and you will find a solution.

[John Smith 2]

[QUOTE=alcomech;14379951]How many stages of heat are there?
What is the resistance of each heat strip?
What is the voltage and phase for each stage of heat.
What is the actual current AMP draw or RLA on each individual heat stage when running compared to listed RLA.
What is the rating for limits or better what is the part number.

With this info it can be easily determined what the minimum required air flow should be and also what your temperature rise will be.



Thanks Alcomech for writing in... and thanks guys for having me here on the forum, I have been reading other posts and threads. This is a great forum with a lot of experience and knowlege. Alcomech remember, above in the post I pointed out that the manufacturer sent their people out and verified adequate airflow at their rated spec's.

[Mr Bill]

This problem could probably be solved, with just a small piece of sheet metal attached to each side of the blower housing at the top or bottom to divert the air more towards the strip, I can't see any liability in doing that. I don't feel the amount of diversion you would have to do would create any airflow issues at all, just a thought.

[jimj]

Alcomech remember, above in the post I pointed out that the manufacturer sent their people out and verified adequate airflow at their rated spec's.

So........... the manufacturer sent there people out and verified proper airflow, but had no answer to your problem? If thats true, I think its time to mention there name!

[John Smith 2]

Mr. Bill, that was a very good observation and response. However, that was tried twice... adding a sheetmetal diverter. However it failed to solve the problem. The "throw" distance from the blower to the evap coil is so narrow; not enough room.

[John Smith 2]

jimj... I'm still trying to work things out with them. It would be far better if when I did mention their names I could come back and tell everyone, "we had "big" problem and mfgr/distr "X" stood by it and made it good."

[jnsrose]

How is the airflow? LOL. Just kidding. Sounds to me you already have your answer, Poor design of the heat strips. So when the manufacturer does not make it right, will you drop there name? Hope for the tenants sake they hurry up it is getting cold. Good luck and I hope you come back with a solution. This has been an interesting read.