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Raypak heater surging

Posted by Clint Combs on November 22, 2010 at 9:23pm in Pool Service Topics
Has anyone else ran into a Raypak/Rehm low NOx heater that surges when it is running? (The flame surges up nice and blue, then dies down, then surges up again, over and over.) 

I first discovered that the heaters that do this would run smooth if I put my hand partially over the inlet for the blower. In order for this to work without leaving my hand there, I sandwiched a small piece of metal between the blower and the sheet metal plate that it mounts to. (I have used a 3" segment of hose clamp and a flattened conduit clamp for this.) This insert partially blocks the air inlet. Less air produces a steady normal looking flame.

This seems to work. Has anyone else used this method? What else has been used? Do you foresee any problems with this fix? I have used it about 4 times over the last 2-3 years without any ill effects.

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Replies

  • Jeremy Hine December 8, 2010 at 9:36pm
    The Lochinvar heaters work like this too. The entire cabinet is sealed and to test the unit after repairs you MUST button it back up to run. A real pain in the arse sometimes, but getting the proper air mixture is critical to its performance.

    -Jeremy
    Florida Leisure Pool & Spa
    www.FLLeisure.com
    Florida Leisure Pool, Spa, Hot Tub Repair, Pumps, Filters, Heaters, Salt Chlorinators, Automation
    We repair pools, spas and hot tubs, pumps, motors, heaters, filters, automation equipment in Gainesville and North Central FL
  • Clint Combs December 7, 2010 at 2:52pm
    I just noticed a sticker on the inside front panel of a one year old Raypak low NOx heater. It states that the door must be in place for the heater to work properly. So I guess that we are on the right track. If the heater is surging with the door off, put it on and see if it still surges. Only then would it be appropriate to block some of the air flow.


    David Penton said:
    I too have seen this twice, and what a Raypak tech told me is that it was in fact too much air.

    The only time I experienced this was when I had the front door off of the LoNOx heaters. As soon as I put the door back on the front of the heater you could hear that everything calmed down...

    The Raypak doors have the rubber seal around them which causes them to seal up pretty tightly (and can sometimes be a pain to put back on properly). I wonder if you may have a door that is warped or the rubber seal was removed, and somehow it is allowing too much air into the combustion chamber -- I am totally guessing here!
  • Jeremy Hine November 25, 2010 at 2:32pm
    Lochinvar heaters are also sensitive to the door sealing propely. I hadn't thought about that.
  • David Penton November 25, 2010 at 12:32pm
    I too have seen this twice, and what a Raypak tech told me is that it was in fact too much air.

    The only time I experienced this was when I had the front door off of the LoNOx heaters. As soon as I put the door back on the front of the heater you could hear that everything calmed down...

    The Raypak doors have the rubber seal around them which causes them to seal up pretty tightly (and can sometimes be a pain to put back on properly). I wonder if you may have a door that is warped or the rubber seal was removed, and somehow it is allowing too much air into the combustion chamber -- I am totally guessing here!
  • Clint Combs November 24, 2010 at 2:01pm
    I am not sure if the issue is elevation related. My regular service area (in which all these issues occur) goes from about 240 feet above sea level to around 1800 ft.
  • Clint Combs November 24, 2010 at 1:49pm
    It does on their low NOx RP2100. It is on the inlet side. It blows air into a box built around the manifold and from there around the jets into the combustion chamber.


    Luke Norris said:
    Jeremy, THe raypak doesn't have a blower.
  • Jeremy Hine November 24, 2010 at 7:39am
    Clint I've only experienced air flow issues w/ the Hayward's FD Inviersal H series. By bending up the tab on the plate that holds the flame sensor. For this issue you've descirbied to be so hit or miss, I'm not sure that its a blower speed issue. Are you having altitude issues? Any advice from the fine folks in Oxnard, CA from Raypak?

    -Jeremy
    Florida Leisure Pool & Spa
    www.FLLeisure.com

    Clint Combs said:
    I don't think it is a gas volume / pressure issue. I can dial that in fine, but you are certainly right to point that out as a first step. The heater just seems to have too much air. Jandy heaters have an adjustment for this that you can set during installation for various altitudes. So, I figured that I would add that adjustment to the Raypak. Once I block part of the air inlet, the heater runs smooth and the manifold gas pressure meets specs.
    Florida Leisure Pool, Spa, Hot Tub Repair, Pumps, Filters, Heaters, Salt Chlorinators, Automation
    We repair pools, spas and hot tubs, pumps, motors, heaters, filters, automation equipment in Gainesville and North Central FL
  • Clint Combs November 23, 2010 at 9:07pm
    I don't think it is a gas volume / pressure issue. I can dial that in fine, but you are certainly right to point that out as a first step. The heater just seems to have too much air. Jandy heaters have an adjustment for this that you can set during installation for various altitudes. So, I figured that I would add that adjustment to the Raypak. Once I block part of the air inlet, the heater runs smooth and the manifold gas pressure meets specs.
  • Jeremy Hine November 23, 2010 at 7:39pm
    what does you mnenometer tell you? too much or not enough pressure could affect combustion such that its starving for air and you're now having to throttle the air flow w/ your hand.

    (yeah...,what those guys said down below)

    -Jeremy
    Florida Leisure Pool & Spa
    www.FLLeisure.com
    Florida Leisure Pool, Spa, Hot Tub Repair, Pumps, Filters, Heaters, Salt Chlorinators, Automation
    We repair pools, spas and hot tubs, pumps, motors, heaters, filters, automation equipment in Gainesville and North Central FL
  • Lester Eric Brehm November 23, 2010 at 8:21am
    What Bruce said,I would first check gas pressure at heater with every gas appliance on that line under load.I would also check the orientation of the second stage reg if it is a 2 lb second stage the ones I've seen must be mounted vertical from the line not horizontal.
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