primary/secondary

steven_5

Thank you for the input
The heat loss is 80,000 and Buderus boiler is 96,000 net. The next smaller boiler nets at 75,000.
I will look into the thermostatic by-pass valve.
The Taco 0010 still seems like alot of flow.(30 gpm @ 3.5 ft) Is it really needed? Would the 007 be better 19 gpm at 3.5 ft?

STEVEN MARKS

primary/secondary am I right?

I am installing a new gas boiler 112,000 btu output on a converted gravity hot water system.
Radiator EDR is 465
Heat Loss about 75,00 BTU/HR
According to Steamhead's chart I should use a Taco 007 which would give me about 19 gpm at 3.5 ft head.
If I am right and understand primary secondary I dont want or need 19 gpm flowing thru my boiler as this would give me a lower delta T keeping my boiler in condensate temperature longer.
My primary pump I selected a Grundfoss 15-42 which would give me about 14 gpm at 3.5 ft head. This would in turn give me about a 15 degree delta T across the boiler.
Is my understanding correct of primary/secondary correct?
Where do I install my common piping? Some manufactures show it on the system side (secondary) some on the boiler side (primary). Does it matter? Either way I get 14 gpm flowing thru my boiler.
The boiler is a Buderus with outdoor reset. (Logomatic control 2107)
Thanks for any input
Steven

STEVEN MARKS

Any thoughts?

Am I on the right track?

[Deleted User]

Which Buderi...

Some of their boilers already have a system of avoiding condensate production. In using their control logic, it also has "pump logic", whcih will also protect the boiler from long term condensate production potential.

For the ultiamte in protection, I recommend the use of a Thermic bypass valve. THis will guarantee the boiler will never see any condensate production.

But, if you were me, you'd be installing a modulating/condensing boiler, and then you wouldn't be asking these questions :-)

ME

Mike T., Swampeast MO

If this is a plain boiler and a simple gravity conversion (no attempt to zone the system via pumps or valves), then I believe you should use a thermostatic bypass valve type ESBE available from Danfoss and others. This will allow just enough flow through the boiler to ensure return temperature above any possible problem point with a reasonable delta-t across the boiler.

Size the replacement boiler properly according to load--NOT OVER BUT CONSIDERING the I=B=R rating. This could easily be sizes smaller than the existing boiler.

Once the system is up to temp, the high secondary flow will ensure something near the original flow balance through the radiators. The delta-t across the rads will be small in most weather but the delta-t across the boiler will at least be in the bounds of reasonable efficiency in weather conditions that require a good chunk of the boiler's output.

Oversize the boiler extremely--far too common--and it won't even get a chance to operate near its best efficiency!!

steven_5

Buderus G124X/32II

Most people I have spoken with recommended a Taco 0010 to account for the gpm needed in a gravity conversion and install a boiler by-pass.
Customer didn't want to pay the upfront cost for a mod/con boiler. They may be moving back to the west coast in next couple of years.
Buderus does have condensation logic built into the Logomatic control by keeping the pump off until the boiler reaches 110.

kevin coppinger_4

A 15-58 on spd.

2 would be fine. If you are using the 2107 I would then use the indoor BFU sensor to run the system on constant circulation...that will maximize comfort and fuel savings....Buderus ,when I have talked w/ them says the other stuff is really a waste of time. I have 2 systems out there like this and the customers love them.

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