Why do Raypak boilers pump away?

Unknown

I thought the same as you have sugested

*What would you think the MFG will say IF I pipe it primary/secondary like I originally thought to do when I looked at this botched installation?

Attached is how it stands today.



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Unknown

Seems strange

*Seems strange to me that Raypak's residential boilers come preassembled with a Taco circulator on the return side of their boiler.

*This normally doesn't bother me. I thought I would just move it to the other side Pumping Away. However, this boiler (H-30090R) has a 3/8" copper bypass that attaches the boiler manifold to the suction side of the circulator. It's there to protect the boiler. This copper fin boiler can withstand return water temperatures down to 105ºF. I like that because it's hooked up to a high mass radiant slab.

*The Factory sent me out a piping diagram showing their circulator pumping INTO the boiler's return. The near boiler piping shows an air elimination device "Air Scoop" and expansion tank on the return(between the circ's suction side & the heating load. Strangely enough, they've got an air vent shown not only ontop of the "air scoop", but ANOTHER one in between the air scoop and the circulator. WHOA? They show the feed water valve downstream of "air scoop" This is Raypak diagram Fig. 8898.1 for those of you with the book.

*Could someone tell me how to appropriately pipe this thing. I'm wanting to tear most of it out and start from scratch but, I know these things can be forgiving and the factory bypass stands in the way of me using a pumping away configuration. What am I missing here?

Oh, If you're online you might be able to catch up & talk live w/ me on AIM. I'm Radiantfloors

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Steve Ebels

They probably want

They probably want the HX to be under as much system pressure as possible to keep it from flashing into steam. This scenario is possible when pumping away from the boiler due to the negative pressure generated by the circ. Especially true when using high flow pumps which are often found on low mass or tube type boilers. I'd still put the expansion tank upstream of the circulator whether it's on the in or out side of the boiler.

hot_rod

You really

to primary secondary low mass copper boilers. They need a lot of flow. As such the circ location really isn't a big deal. Most copper boiler manufactures show pumping towards the boiler.

I'd caution you against trusting that 3/8 bypass to protect that boiler. A cold concrete slab will greatly overpower the ability of that bypass to offer adequate protection.

I've got a barn full of dead copper boilers that attest to the fact they are very uncomfortble at the operating temperatures you mentioned. If you go there, check the HX and entire flue yearly for signs of flue gas condensation. I got a hundred bucks says you see signs of it within a year or two

hot rod

Unknown

Is it possible,

to pump away from the fin tube boiler & ex. tank without using P/S pumping and not risk a steam flash or condensation? Looking for a KISS solution. If not, I'm going to P/S pipe it & fix the rest of the mess the last guy (a fuel provider) made.

*To catch up with me real time, try AIM My user name is: Radiantfloors

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hot_rod

Why not

Just meet the flow requirements and delta T across the HX. Actually those small ones really don't have huge pressure drop.

I've done them several ways. Sometimes I have made the primary loop, the boiler. As such the "loop" is only a couple feet long. So really the pump location is where?? Pumping away or towards?

Or you could have a seperate primary loop and the boiler pumps into it, now it is a secondary. In that mode the pump really needs to be sized to the boiler spec as the piping is generally not an issue.

The two big issues are flow through the boiler, and adequate return water temperature protection. The piping alone will not always provide adequate protection. Copper tube boilers hate going at it unprotected!

hot rod

hot_rod

Here is a little cast boiler

That I will use to replace a hot water heater radiant. I will T-drill a Grundfos MixiMiser into that nude copper section.

Gonna try running a 50 degree delta T (135-185) controlled by the RTI setpoint control, on the boiler to help handle short cycling on this 3 zone system.

hot rod

kevin coppinger_4

now I've really seen it all ....

in a boiler room ...a toilet! I would pri/sec. it...that way you are sure.kpc

kevin coppinger_4

is that a ...

007 on that? looks bigger..kpc

Unknown

Thats Right! Toilet in mechanical room.

WARNING: Methane gas can be dangerously combustable if flame present;-)

Watch your boiler work as you go.

PEX manifold doubles as toilet paper holder.

I don't think that meets the plumbing & fuel gas code unless it's sealed combustion.

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kevin coppinger_4

does that help...

warm the seat on those frosty mornings? Carpet near the boiler? Hmmm...I can see a lot of thing going wrong here...kpc

Unknown

They're likely geting a New Vitodens

The atmospheric boiler's gotta go.

* Anyone looking for a Raypak Residential 64,000 BTU I=B=R Finn-tube boiler? Low... Low... miles. Look for it soon below W/ Dan's approval of course.

*To catch up with me real time, try AIM. User name: Radiantfloors

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