Michael, I am just trying to help with a real world answer to Peter's question. I am sorry if I said something to upset you. I am not trying to be confrontational, just trying to help.
Lowering the RH in a piano by 15% (60-45) requires a specific increase in temperature using the principle of raising temperature lowers relative humidity. Assuming a temperature of 70° F (21C) and 60% RH, we have a dew point of 55°F. If the dew point stays the same (no major weather shift) you would need to raise the temperature 9°F to lower the RH to 45%. Since both the 38W and 50W reach about 140°F, yes, both rods can achieve this. Will the 50W rod get there faster as Michael suggests? Absolutely. But they will both be able to accomplish the same goal. The questions then becomes, will the 38W be struggling so much that it allow the piano to be outside of the optimal zone for long enough periods of time that is will affect the tuning stability among other things? I don't think so, but there are enough variables that I can't possible know that I wouldn't want to say for sure. If it were me, I would probably think it was worth my time to experiment. Anecdotal advice from technicians in other areas of the continent is fine and of some use, but knowing your own market is paramount.
We have 2 different vertical pianos in our test lab right now. They are about the same height, but the interior volume in one of them is much smaller than the other, as well as the smaller one has a lid that has much smaller gaps around it. Both pianos are controlled nicely by the PLSS, but the smaller one has much shorter cycle times. The high to low range is the same, it's just the cycle time that is different. 20 minutes or so for the skinny piano and about 35-40 for the fat one. 55-60% RH ambient.
Jerry's question is "With a 38 watt rod installed, how high can the room ambient RH be and still bring the RH inside the piano to the desired point?" Not that simple to answer I'm afraid. Dew point has a lot to do with it as well, never mind the specific piano as well. I would rather we looked at the 50W rods as being faster. Ultimately, would a 38W Dehumidifier fall short of the performance capabilities of a 50? Yes, of course. Sometimes, even 50W in a vertical isn't enough.
I suggest doing a little experimenting in your own market so that you have first hand knowledge. Become the expert. All the theory in the world doesn't count for anything. How is the piano doing/
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Charles Rempel
Dampp-Chaser Corporation
Hendersonville NC
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Original Message:
Sent: 08-04-2017 09:31
From: Michael Spalding
Subject: 38-Watt Vertical Dampp-Chaser systems
So Peter's original question was whether the 38W dehumidifier would be adequate in a 60% RH ambient. In other words (actually, your words), would it have enough power to reach the humidistat setpoint? Valid question. Or, put another way, would it take so long to reach the setpoint as to degrade the system's ability to control the humidity? Compared in this way, the 50W would outperform the 38W. Peter wants to know if this would be a concern at 60% RH. Can you answer his question?
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Michael Spalding RPT
Fredonia WI
262-692-3943
Original Message:
Sent: 08-04-2017 08:44
From: Charles Rempel
Subject: 38-Watt Vertical Dampp-Chaser systems
I don't think my nonreal answer is flawed in the slightest. Don't forget that the entire operation is overseen by a Humidistat. It is not operating in the vacuum of space. Dehumidifier rods of any wattage are (hopefully) all controlled by a Humidstat which turns them off when the set point is reached. As long as the Dehumidifier is capable of raising the temperature/lowering the RH enough to achieve the set point the result will be the same. The only difference will be the time it takes to get there.
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Charles Rempel
Dampp-Chaser Corporation
Hendersonville NC
Original Message:
Sent: 08-04-2017 08:22
From: Michael Spalding
Subject: 38-Watt Vertical Dampp-Chaser systems
Charles, your thermodynamic analysis is flawed; you might want to check with your engineers on this. Briefly, the important number is not the temperature of the dehumidifier, it's the amount of heat transferred from the dehumidifier to the piano. The 38W dehumidifier, at the same temperature as the 50W but 24% shorter, will transfer 24% less heat. The performance difference is real, and Peter's question is legitimate and deserving of a real answer.
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Michael Spalding RPT
Fredonia WI
262-692-3943
Original Message:
Sent: 08-04-2017 08:09
From: Charles Rempel
Subject: 38-Watt Vertical Dampp-Chaser systems
The entire rest of the world gets only the 38W dehumidifiers in vertical Systems. We get exactly zero requests for higher powered dehumidifiers. Keep in mind that the 38W and the 50W both reach the same temperature. Since one is longer, which gives it more surface area, it will simply raise the temperature more quickly. Depending on the climate, that may or may not be important.
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Charles Rempel
Dampp-Chaser Corporation
Hendersonville NC
Original Message:
Sent: 08-03-2017 23:31
From: Peter Stevenson
Subject: 38-Watt Vertical Dampp-Chaser systems
Hello all,
Has anyone had enough experience with the new 38-watt vertical systems to notice how it compares with the 50-watt vertical systems? We don't have a very humid climate up in northern BC, but some households are in the 60%s RH for a couple months.
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Peter Stevenson RPT
P.S. Piano Service
Prince George BC
250-562-5358
ps@pspianos.com
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