MPO 147 Bypass

Unknown · March 2007

The piping diagrams we show in our manuals are recommended minimum piping requirements. More modern methods of piping mixed temperature jobs like yours such as Boiler Loops, Primary-Secondary, Variable Speed Injection, etc. are always above and beyond the bar for any boiler job. If you are using standard thermostatic valves for the radiant, the only time you will experience substantial flow from the radiant side returns is during startup. The boiler is fine down to 100°F but you will probably be having to maintain the boiler on standby for the radiant in order to get any heat to it.

It would make more sense to utilize an injection mixing control that can establish two different temperatures for the baseboard and radiant, take charge of Indirect Priority functionality and also take charge of firing the boiler only to maintain certain main temperatures needed for the baseboard, Indirect and radiant while at the same time utilizing outdoor reset functionality. The Tier 3 BSC Control we offer takes charge of all this and very effectively.

http://www.burnham.com/PDF/Tier3_I&O.pdf

Glenn Stanton

Manager of Technical Development

Burnham Hydronics

U.S. Boiler Co., Inc.

Roy_10 · March 2007

MPO 147 Bypass

Anyone notice that the Burnham MPO147 piping diagram changed at the begining of the year? It used to have the indirect water heater piped into the bottom of the unit and have a boiler bypass. The New diagram did away with the seperate indirect water heater return and changed the boiler bypass to a system bypass. Anyone know why this change was made? An interesting side note, both the MPO147 and MPODV(direct vent)unit both were piped the same but the change was only made to the MPO147. Both (revised)drawings are on the Burnaham site page 23

Unknown · March 2007

Roy

Thanks for bringing this to light. Our Engineering Dept. has been in the process of readdressing the use of bypasses on various hot water boilers. Since there are indeed boilers that are not tolerant to cooler return water temperatures for prolonged periods of time, a decision was made to update the manuals for those boilers to incorporate System Bypasses in lieu of Boiler Bypasses. For some reason this inadvertently also got carried over to the MPO boiler. This is in error and will be corrected on the website immediately and in the next printing of manuals. The MPO is very tolerant to cool return water due to it's internal blending technology.

The Indirect Return piping still wants to be piped to the bottom rear tapping as shown in the very next pages of the manual just as it always has. We apologize for any confusion this has caused and once again thank you for bringing this to our attention. I have posted the diagrams that you should be using below.

Glenn Stanton

Manager of Technical Development

Burnham Hydronics

U.S. Boiler Co., Inc.

lchmb · March 2007

question

Glenn, while you have a second (hoping here), what would Burnham like in reference to piping while dealing with radiant zone's?

I have a system to install that will have two zone's of baseboard, a superstor and 3 zone's of radiant. Should I pipe in the bypass or do primary/secondary or does the MPO like this cool return temp?
Thanks for any information..

lchmb · March 2007

excellent

Glenn thank you very much for your time. I've been looking forward to installing another. Unfortunately I spent most of the winter doing gas work.
The other MPO, which we had discussed, is running exceptional! Last time I discussed the system with the home owner he was still impressed with the boiler. His fuel bill's are down and the noise level dropped a ton!!

Thank you
Tom

Unknown · March 2007

Glenn , another question

What if an indirect's return pipe was connected in to the heating zone return port ? Does this significantly decrease the recovery of the indirect ? Not that I would do that , just wondering in case I see it in the future .

Unknown · March 2007

Ron

If all of the zones were running high temperature with minimal temperature drops, then piping the indirect in with them is not really an issue. It's when there is a difference due to system reset and other things such as radiant operating that warrants the bottom return tapping. You will always appreciate quicker recovery though by piping the indirect into the bottom return tapping since it is primarily utilizing the hottest available water in the boiler which happens to be in the rear section.

Glenn Stanton

Manager of Technical Development

Burnham Hydronics

U.S. Boiler Co., Inc.

Roy_10 · March 2007

Rear section

Why does the rear section of these boilers seem to build up a white sheath? Is it just because it's the hottest part of the boiler?

Unknown · March 2007

Roy

I'm assuming that by "white sheath" you are referring to white powdery deposits? This is more than likely the byproducts of efficient combustion and you will see more of it back there due to the flue gasses accumulating and turning 180° to make the second pass toward the front of the boiler.

Glenn Stanton

Manager of Technical Development

Burnham Hydronics

U.S. Boiler Co., Inc.

Roy_10 · March 2007

Thank you

Thanks Glenn, Yes I've been seeing the back section on several triple pass boilers coated white. Was concerned that the white build up was acidic and would attack the heat exchanger. Sounds like this is actually a good thing and I do have the burners tuned properly. Other than the white coating the exchangers are nice and clean and boilers are running at their rated efficiency.

MPO 147 Bypass

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