Raypak Heater temperature has 5 degree difference then water

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Masspools

Masspools

0
In The Industry
Jan 22, 2013
35
Cambridge Massachusetts
Hi All

I have installed a Raypak Digital Heater 206k BTU Natural Gas in a commercial facility. The heater display shows the set point at 104 degrees and the heater only heats the water to 99-100 degrees. There are no errors. I left it for a day and the the heater changed course and had a set point of 108 and water temperature of 103 without me touching it. I have changed the board (sent to me by Raypak) and the temperature sensor has been changed. Has anyone run in to this problem and what is the solution.

Many Thanks

James
 
It is completely normal for a heater to raise the temperature by 4-5 degrees. If you keep doing that for a long time the water will eventually get to the target temperature. As it approaches the target temperature, the water coming out of the heater will be above the target temperature, even though the bulk of the water in the pool/spa has not reached that temperature yet.

On the other hand, the target temperature shown in the display should not be changing unless someone changes it.
 
I install almost 200 Rheem's each year and I have never to date experienced what you are seeing. You say it's installed in a commercial setting. What are you heating with it? To get to a set point of 108 on it's own is weird. What are the first four digits of the serial number on this unit?
 
Hey Guys

Thanks for replying back, I checked the temperature of the heater today and it was reading on the display 104 set temp and 104 actual temp. I have a digital thermometer and tested the pool at 100. The pool is 15,000 by the way. I talked with Raypak and they said it could possible be the unitherm governor, this is the first time I have heard of this problem in my years in the field. I also checked the Faults menu (press up button and mode together for 5 seconds) There were a list of faults like Water Sw and sensor fault. These are things that I have replaced, i.e. board and temp sensor. Do you guy know based on your knowledge if the governor would be something worth replacing?
 
You keep a pool at 104 or is this just a large spa? Also kind of interesting that you would have used such a small heater, 206. You may find that the unit has to work more to keep the water warm that it could have a short life span.

I haven't seen any unitherm governor issues with this unit. I would certainly keep my eye on this heater for a while.
 
I sized the heater based on the one being replaced, it is in an indoor environment with a dectron system, but a do understand your concern about the size, if I look back I should have gone with my gut feeling and got one with more BTU's.

An Update, I replaced the unitherm governor today, the old one has a rusty film on it, I have come to a conclusion that when they test these units, a little water may still be in the manifold and with being in a warehouse for so long that it was starting to corrode. When I turned the heater on the temperature immediately read what we were getting in the pool/large spa and there were no faults reading on the display. I did just a get call from the manager saying the water has not warmed up yet but it has only been 2 hours. Keep you posted.

Serial number# 1312370034

Thank you to All who contributed!
unitherm governor bottom.jpgunitherm governor top.jpg
 
Hi guys
just to catch up on the problem with this heater and the result of the real problem. The internal by-pass in the heater manifold was stuck open. To give a better explanation, the internal by-pass is located on the outlet side of the heater. What happen when it is stuck open the water flows directly through the inlet to the outlet by-passing the heater exchange, the water will not heat up to max temp. With the by-pass closed, the water passes through the heater exchange, when the governor senses the temperature increase it opens up and allows water out through the output.
 

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December of 2013 is when that heater was manufactured. It is not uncommon to see rust in the header. As pointed out earlier, the heaters are test fired at the factory, and will retain water. While the cast iron headers used to be a porcelain coat, now i think it's some kind of dip coating, powder coat like the outside, or may still be porcelain. Anyway, it looks a lot like the coating on the outside of the headers, and it is not always a perfect coat apparently, since you will get rust in most heaters. I guess the time between manufacture and "inservice" hasn't been long enough to be a problem to Raypak with regard to rust.

The heater is designed to have a certain amount of flow through it, and excess is routed through the mechanical by-pass (MBP). This amount of opening with change throughout the heating cycle(s). There is also a certain temp that is desired through the exchanger, and when the temp rises to the optimum temp (105-115) the thermostatic by-pass (governor or TBP) opens and allows water to exit the exchanger.

Example: When heater is first fired, the MBP is open the most because the TBP is closed due to the water being cool, and since no water is allowed to leave the exchanger at this point, the MBP is handling all the water. As the water in the exchanger heats up, the TBP will begin to open, causing the MBP to close down to its FLOW regulated opening. This is the "moan" that is sometimes heard moments after the heater is first fired. It is the water beginning to move through the exchanger and out through the TBP.

Does this make sense??
Sorry if some or all is a repost.
 
IMO Thats why its our responsibility to sell them am ASME so the heater doesn't fail prematurely. We used to sell commercial properties the polymer headers, but because of the almost constant running they were subject to, especially with spas, they were failing sooner than they should. The constant heat would warp the headers and the heater would have a terminal leak. Once we began requiring the use of the ASME, the longevity shot way up. Just our experience. Your results may vary...
 
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