Cleaning RayPak heat exchanger

[Eric H]

I was working on a RakPak floor heat boiler today. The flame was coming out of the front of the boiler and not all of the burners were lite. I pulled the burner assembly out and cleaned all of the jets/orifices but the flame is still lapping up the front of the boiler. I don’t think there is enough draw up the flue because the heat exchanger looks pretty dirty. Any advise on cleaning that? I took a photo looking up from where the burner sits

 

[New Washdog]

I was working on a RakPak floor heat boiler today. The flame was coming out of the front of the boiler and not all of the burners were lite. I pulled the burner assembly out and cleaned all of the jets/orifices but the flame is still lapping up the front of the boiler. I don’t think there is enough draw up the flue because the heat exchanger looks pretty dirty. Any advise on cleaning that? I took a photo looking up from where the burner sits

A couple of years ago we had a boiler that was giving issues with ignition. We (gas technician and I) had to remove the secondary heat exchanger of one of our Rinnai boilers and clean it. We used a multipurpose cleaner spray and rinsed it thoroughly in a wand bay, dried it with compressed air and reinstalled it. It has been working fine since.

 

[mjwalsh]

I was working on a RakPak floor heat boiler today. The flame was coming out of the front of the boiler and not all of the burners were lite. I pulled the burner assembly out and cleaned all of the jets/orifices but the flame is still lapping up the front of the boiler. I don’t think there is enough draw up the flue because the heat exchanger looks pretty dirty. Any advise on cleaning that? I took a photo looking up from where the burner sits

Eric ... has make up air ... negative air pressure ever been an issue during the life of this specific boiler. My thoughts based on a 1980 400K boiler not ever showing signs of burner assembly etc soot.

I remember when I was involved in some rental property of having to needing internal cleaning. We called a plumbing & heating contractor & they pumped a special chemical ??? through the internal pipes through the heat exchanger itself. It made a world of difference ... not sure of the specific how & why ... since that is somewhat separate from the burner assembly. Maybe the flame is overwhelming your partially plugged heat exchanger???

 

[MEP001]

Make sure the main valve isn't opening before it ignites. I've personally seen this, the flameout can blow out the pilot and it will send fire everywhere. Someone here recently posted with the same problem.

 

[MEP001]

We called a plumbing & heating contractor & they pumped a special chemical ??? through the internal pipes through the heat exchanger itself.

Completely and totally unrelated to this issue. They descaled the burner.

 

[mjwalsh]

Completely and totally unrelated to this issue. They descaled the burner.

In that specific case of the relental property ... they cleaned the heat exchanger within some 80% efficient Hydrotherm hydronic boiler.

It would be nice if you would quit trying to gaslight posters who post in "good faith"!

 

[MEP001]

In that specific case of the relental property ... they cleaned the heat exchanger within some 80% efficient Hydrotherm hydronic boiler.

They cleaned the inside to improve water flow. Eric H needs to clean the outside to improve air flow. Your comment is both unhelpful and off-topic.

It would be nice if you would quit trying to gaslight posters who post in "good faith"!

I'm not trying to gaslight you. You're either trying to derail the thread or you're so ignorant you don't even realize how ignorant you are. You need to look up the meaning of "gaslight" and study the proper use of quotation marks.

 

[Randy]

I was working on a RakPak floor heat boiler today. The flame was coming out of the front of the boiler and not all of the burners were lite. I pulled the burner assembly out and cleaned all of the jets/orifices but the flame is still lapping up the front of the boiler. I don’t think there is enough draw up the flue because the heat exchanger looks pretty dirty. Any advise on cleaning that? I took a photo looking up from where the burner sits

Eric, what you’re getting is called “Flame roll out” and is a very dangerous problem and the boiler should shut down when the roll out sensor senses the problem. This is caused by lack of draft up the flue. In your case it’s caused by a plugged up heat exchanger. You’re probably going to have to tear down the boiler, remove the heater exchanger, clean it and reassemble to boiler. I’ve seen people clean the installed. But makes one hell of a mess.

 

[HeyVern]

Heat exchanger is definitely plugged. Once you get it clean, check the flame on the burner, it should be mostly blue not orange. If not adjusted right, the flame will be mostly orange and produce a lot of soot.

 

[Eric H]

Thanks for the responses. This isn’t my wash I’m trying to help out a friend. I was called because the boiler wasn’t working at all. The transformer had shorted out. Once we got the transformer replaced I noticed the 3-4 of the burner tubes weren’t lite. We pulled the burner tray and cleaned the nozzles/orifices and now that works great except there doesn’t seem to be enough draw. The photo I attached to the original post was of the heat exchanger. I took the photo when the burner tray was removed and suspected it was too dirty.
There are some other issues that I need to fix on this system. I’m just trying to get the guy operational for now.
We might just have a plumber/HVAC guy clean the heat exchanger. I don’t mind taking my own stuff apart but I don’t like learning how to fix stuff when someone else is paying for any mistakes I make.

 

[Greg Pack]

Has anyone checked the flue?

 

[GoBuckeyes]

Eric H which burners were plugged up? Were they on either side of the pilot? I just had this issue with my Raypack. When the main valve would open I was getting massive roll out so I figured the heat exchanger must be sooted like your friends. In my case, the pilot would light, thermocouple would open the main but since the jets next to the pilot weren't letting any gas out there was a delay which would cause a giant rollout and blow out the pilot.
I didn't realize that was my problem until later and I didn't want to disassemble and remove the exchanger because its a two person job, it's heavy and awkward lifting it out and you'll usually ruin the firebrick in which case you'll need to order more. What I did instead was slide out the burner tray as well as remove the draft hood. Once the hood is off and you can get to the top side of the exchanger where there are several long angles that sit between each tube bundle on top of the fins. They're held in place by a couple of cross pieces with twisted wire. If you remove what you need to to get the angles out you can then use a fine pick between all of the fins to basically poke or knock off the soot or corrosion that is on the bottom side of the exchanger. Compressed air and a shop vac will be needed as well. once done, vacuum out the entire boiler and reinspect from below and see how you did.

 

[mjwalsh]

Eric H which burners were plugged up? Were they on either side of the pilot? I just had this issue with my Raypack. use a fine pick between all of the fins to basically poke or knock off the soot or corrosion that is on the bottom side of the exchanger. Compressed air and a shop vac will be needed as well. once done, vacuum out the entire boiler and reinspect from below and see how you did.

Just to add to GoBuckeye's post ... there should be some attention to the "root cause" of the "sooting". Not the least of which ... could be the original installer not having adequate "away from obstructions" in line with the top of the vertical vent pipe!

A top notch HVAC person &/or a great inspector ... once he or she sees the actual install ... can probably explain it better than some of our remote forum attempts to Eric & the friend he is trying to help out!

 

[cantbreak80]

there should be some attention to the "root cause" of the "sooting".

The "root cause" is closed combustion air vents in the equipment room. Or, improper or closed boiler by-pass valve. Or, both!

Operators who block the equipment room vents save on heating expenses and eventually pay for it with heavily sooted atmospheric boilers.

Closed or Improper by-pass (boiler protection) valves create excessive condensation in the stack which results in "acid rain" dripping onto the tube bundle.

In my experience, cleaning tube bundles works just fine for one or two heating seasons...then, you get to do it all over again. For best results replace the tube bundle and expect to replace most of the refractory while you're at it. Or pay once and cry once with a properly plumbed ModCon boiler.

 

[Eric H]

The "root cause" is closed combustion air vents in the equipment room. Or, improper or closed boiler by-pass valve. Or, both!

While the equipment room certainly isn’t very well sealed I don’t think there is any provision for make up air. The front door opens out and there doesn’t seem to be negative pressure when opening the door. I’ve experienced negative pressure holding doors closed before. It is certainly a unique and disturbing situation.
I’m not sure there is a bypass valve installed on this system. If there is I do suspect it is closed.
next time I to this wash to clean the heat exchanger I am going to install an outside air stat and a return line stat. The system currently runs solely on a slab stat set to turn on at 45 degrees.

 

[cantbreak80]

Eric,
My library of Raypak manuals has long been discarded. However, here's a copy of a DHW boiler manual from Huron Valley Sales' website.
Page 12 outlines the make-up air specifications for similar hydronic boilers. RayPak Manual

No by-pass valve? If so, the boiler is "seeing" cold glycol at the tube bundle for a very long time on it's initial call-for-heat. This causes condensation in the flue. When combined with flue gasses, the condensation drips onto the tube bundle. Acidic condensation and soot equals bad news. Incomplete combustion due to reduced make-up air...Double Yikes!

If my state boiler inspectors saw that it would result in an immediate Red Tag. One of them recently tagged a ModCon...the T&P valve was plumbed to about 13" above the floor. I soldered another 7" to it to meet code ("within 6" of the floor.")

 

[MEP001]

While the equipment room certainly isn’t very well sealed I don’t think there is any provision for make up air. The front door opens out and there doesn’t seem to be negative pressure when opening the door.

The air draw from the boiler draft isn't very strong, certainly not strong enough to feel as resistance when opening the door. The fact that the door opens out and (assuming) it doesn't have a vent in it could be compounding the soot issue.

 

[Eric H]

The air draw from the boiler draft isn't very strong, certainly not strong enough to feel as resistance when opening the door. The fact that the door opens out and (assuming) it doesn't have a vent in it could be compounding the soot issue.

The door that was stuck closed was not this Carwash. There was a story from my old distributor where he installed a million BTU boiler at a wash, started it, went out for a smoke and they couldn’t pull the door open. The boiler had sucked out enough air to pull a vacuum. They had to cut power to the building and wait for the room to equalize to the outside to get back in and cut some holes in the wall.
I experienced this same situation while doing some maintenance work at a sugar processing facility that supplies the local Pepsi bottling plant. I opened the door but there was a whooshing sound and considerable resistance on the door. A company had been in weeks before to “weatherize” and air seal the building. No one had considered the makeup air. Head maintenance guy said that the door I opened was usually open 24/7 so they were only having occasional issues. That’s were my involvement with that issue ended. I don’t know what their resolution was.
But, back to this wash....I doubt there is insufficient makeup air. There just isn’t vent holes cut into the wall like I had. I’ve covered my makeup air vents because everything is high efficiency, drawing air from outside

 

[Eric H]

Just a quick follow up. Cleaned the heat exchanger yesterday. It’s drawing much better now! The first pic was after we had already vacuumed some junk out. Bottom is cleaned.

 

[Randy]

Looks good, how did you clean it?