Second opinion

[PAnderson415]

I had a Carrier FE4A with a Carrier air purifier installed in February of this year along with a Carrier 25VNA heat pump. This weekend on the hottest day of the year I noticed that water was leaking from the fan coil. I took the filter out and it was sopping wet. I called the installing contractor and he said it was the result of a frozen coil caused by a dirty filter. Here's why I'm not convinced that a dirty filter was the root cause of the problem.

The FE4A adjusts the blower RPMs to achieve the targeted airflow. So even if the filter decreased the airflow, the blower would compensated for the reduction.

Here's what I think is going on and would appreciate you assessment.

The fundamental problem is an inadequate condensate trap.

I see two problems: the outlet is at the same level as the drain pan and the trap is far too shallow. I suspect that when the fan gets going it sucks the water out of the trap preventing the pan from draining. A degraded filter could exacerbate the problem but I believe the fundamental fault is in the trap.

The manufacturer specs for the trap are as follows:

I had pointed out the discrepancy between the specs and the installed trap a the final inspection, but the contractor assured me that the trap was appropriate.

Any thoughts? The contractor is making a service call tomorrow to inspect the unit.

Thanks,

Paul Anderson

[beenthere]

Trap should be deeper. But it is possible that the air filter is dirty enough that it allowed the blower to put enough negative pressure on the drain pan to hold the water up enough to over flow the drain pan. How dirty is the filter.

[PAnderson415]

Trap should be deeper. But it is possible that the air filter is dirty enough that it allowed the blower to put enough negative pressure on the drain pan to hold the water up enough to over flow the drain pan. How dirty is the filter.

New filter was installed in May.

The system is supposed to send a message when the filter is dirty. It does an assessment once a day with the blower at full speed tracking static pressure. It last reported a static pressure of .10. Could the static pressure be artificially low because the blower is sucking in air from the shallow trap?

I think I'm going to ask the contractor to put in a new trap according to the manufacturers specifications.

[beenthere]

If it reported a total static pressure of .1". Its reporting a false total static.

[PAnderson415]

If it reported a total static pressure of .1". Its reporting a false total static.

That was when it was running on low RPM/low CFM. In a flow test (1050 CFM at 950 RPM) the static pressure was .57.

[beenthere]

So is this a 2.5 ton, or 3 ton unit.

[PAnderson415]

3 ton

[beenthere]

Ahh, so at the nominal1200 CM a 3 ton usually gets set to.The static will be much higher.

[PAnderson415]

So... air infiltration from the trap or somewhere else?

[hvacrmedic]

Yes, that trap is actually worse than no trap at all. Make them come back and do it right.

[PAnderson415]

I had them come back and install a proper trap for the condensate drain on my Carrier fan coil (although they didn't provide a clean out so it will have to be taken apart if it becomes clogged). After they left, I discovered they had put a vent on the secondary/overflow drain.



Does this make any sense?

I can see no point in having a simple vent on the overflow. Since the fan coil is under negative pressure, a vent is simply going to draw air from the utility closet into the system, bypassing the filter. My inclinationis to put a cork in it.

Views?

Thanks,

Paul Anderson

[beenthere]

No sense at all.

[vstech]

The vent MUST be removed. I usually install float switches in that location. Sealed, with overflow alarm.

No clean out? I’m always surprised at this… how hard is it to install a tee?

[jbhenergy]

The vent MUST be removed. I usually install float switches in that location. Sealed, with overflow alarm.

No clean out? I’m always surprised at this… how hard is it to install a tee?

$1.50 hard…
Kinda like pvc unions. I do 1 sometimes 2 on units.


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