p/s piping or bypass

polcat1p

should i p/s or put a bypass on my biasi b10-3?

i have a indirect, with 2 heat zones, and a honeywell aq251.     1-1/2 story clay chimny(30years old)thats in good shape. 1000sq ft raised ranch

 im just hear alot of talk about FGC, and dont want my new boiler to fail. am i over thinking this? 

thanks

meplumber

What is your radiation type?

With that boiler, I would only worry about Flue Gas Condensation if my return water temps were in the 110* range for extended periods.  Like with radiant or by using an aggressive outdoor reset.  In either of those cases, I prefer P/S over a bypass.  The piping is more, but the end result is better.  If you are using high to moderate temps, that casting is less suseptable (sp?) than some of the older castings.  But regardless of casting, long term exposure will cause problems.



Give us some idea of your design criteria.

polcat1p

boiler

i was going to pipe the supply to the wall then turn., go about 2' then 1'' spirovent. then go about a foot then put wilo 3speed pump. after that i was going to put  3 sets of 1x3/4 closley spaced  tees. first for the indirect, then the other set of tess for the 2 heat zones(suntem reg baseray). then i was going to drop down, and pipe back to the return. pretty much a big loop. im not sure wher to put supply and return sensors from the aq251? i read the manual, and they said to put one on the supply and return next to the boiler.

all zones will have wilo 3 speed pumps with check vavles.

polcat1p

piping

kind of like these. these are jobs i done a few years ago

icesailor

P/S, Bypass:

It looks like the perfect application for a low loss header or hydraulic separator

The best of all worlds. Boiler circuit is whatever, system flow is whatever, and they all meet in the middle. Better than closely spaced tees.

IMO,

James Day_2

piping

The only thing with P/S the way you have it is mixed temperatures.  You will not get the same temp to every radiator or heating loop.  By the time the hot water sees the last set of P/S tees it may have dropped 10 degrees or more.  Also if you can, use a Hydro Separator.  Then you can zone with zone valves this way you are not over pumping each circuit and you can get a better Delta T throughout the heating system.  I would still zone the Indirect with a Circulator for better recovery. JMO

Greg Maxwell

Biasi piping

Come on guys, its a 2 zone 1000 sq' raised ranch! Hydro seperators? Primary Secondary? We have been distributors for Biasi for around 18 years, and have sold literally hundreds of b10 boilers in every configuration possible, and in every situation possible. Unless you have a very high volume system, which you dont, dont worry about P/S or a bypass, or a hydro seperator. All that will do is drain your wallet. Use your AQ251 with a lo limit of about 130-140, and let er rip. You wont have to worry about return water temps at all. I have heard people say to use lower return temps, but I personally dont recommend it, you are only asking for trouble with condensation much lower than than that. Keep it simple.

polcat1p

pics

i did do a simple primary secondary. i know have to try and figure out the controll settings. any have any input as to where to put   s/r  sensors?

Greg Maxwell

S/R sensors

Put one on the riser as it comes from the boiler supply, then one at the return just before going back into the boiler.

Ironman

Circulators

The primary and indirect circs need to be turned so that the motor shaft is horizontal, not vertical. You'll have a pump failure with the current position.



I would also swap the primary with the indirect circ. That way you can slow the primary down if necessary to prevent short cycling the boiler if the primary Delta T is too low. The indirect circ should be run at full speed.



Nice looking workmanship.

Ironman

Also...

If you connect the indirect circ directly to the supply and return, before the primary circ, you wont have to run the primary during a domestic call. This is assuming that you give the domestic priority.