Low Mass vs High Mass

qmiester

Is there any savings over the long term with efficnecy using a high mass boiler vs a low mass boiler with a copper base board heating. What would the pros/cons be

Thanks for any help.

Brad White_9

Guess What? It depends....

The advantage of low mass is quick response but if we are talking copper fin boilers the boilers tend to be on-off atmospheric or at best two-stage. That means a lot of cycling when departing from their winter design into warmer weather. Flow has to be practically constant so primary-secondary is the best way to control these. If they short-cycle, the solution is often to add a buffer tank (mass), which kind of defeats the purpose....

Higher mass has a durability advantage, plus can accomodate modulating fire with the right burner...

If you are talking low-mass modulating condensing, you have the best of all things.

Traditional High Mass looks something like this:

Confiteor Deo omnipotenti, beatae Mariae semper Virgini, beato Michaeli Archangelo, beato Joanni Baptistae, sanctis Apostolis Petro et Paulo, omnibus Sanctis, et vobis, fratres, quia peccavi nimis cogitatione verbo, et opere: mea culpa, mea culpa, mea maxima culpa. Ideo precor beatam Mariam semper Virginem, beatum Michaelem Archangelum, beatum Joannem Baptistam, sanctos Apostolos Petrum et Paulum, omnes Sanctos, et vos fratres, orare pro me ad Dominum Deum Nostrum.

Uni R_2

Excommunication

Brad that was funny. Too bad the Jesuits are probably on their way now under direct orders from the pipe dope... errr Pope.

Ken_40

Et

cum spirito tuo...

heatboy

High mass..............

would be my choice if two stage thermostats can be used. First stage runs the pump and the second stage starts the burner. Almost always get long burner times since the boiler has been purged down before the burner starts. After setpoint is achieved and on the next call of heat, the cycle starts by purging the boiler with any residual heat left in the boiler. I have found that with this set-up, reset is not needed.

hb

Paul Rohrs_4

ROFL

Brad you are in "The Zone". Thanks a ton for the laugh. High Mass.....

Brad will be here til' Thursday, Try the Veal, and tip your waitress.

Regards,

PR

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ALH_4

Mass

A fixed-fire boiler needs mass somewhere in the system. With hot water baseboard there is very little mass in the system, so the mass needs to be in the boiler. I have seen a lot of Raypaks that were connected to baseboard systems, and the cycling killed them early. Well, there are also the heat exchanger leaks and plugged up boilers with smoke and flames rolling out from underneath, but the cycling is a big problem too.

Short answer: Use a high mass boiler. It will provide you with comparable efficiency and much more reliable and, in my opinion, safer service.

-Andrew

ALH_4

Mass

A fixed-fire boiler needs mass somewhere in the system. With hot water baseboard there is very little mass in the system, so the mass needs to be in the boiler. I have seen a lot of Raypaks that were connected to baseboard systems, and the cycling killed them early. Well, there are also the heat exchanger leaks and plugged up boilers with smoke and flames rolling out from underneath, but the cycling is a big problem too.

Short answer: Use a high mass boiler. It will provide you with comparable efficiency and much more reliable and, in my opinion, safer service.

-Andrew

hot_rod

Not a lot of high mass out there

these days. traditional cast iron boilers have shrunk considerably in size and water content. not a lot heavier than a copper fin boiler.

About the only true high mass would be the Viessman Vitola, or what ever it's called theses days.

In leiu of high mass, modulating boilers seem to handle varying loads rather nicely. match the boiler output to the load, almost exactly, and the mass issue is a mute point.

I hope to see a boiler that will modulate from 1K to full output. It may not be as far fetched as you think.

Areco has a commercial mod con that ranges from something like 300k to 1 million. No reason that could not be accomplished on a 150K boiler or smaller.

It would fire in October and never shut down all heating season. How's that for low cycling and related wear. Makes the F09 & F10 a distant memory if the burner never has to shut down

hot rod

Uni R_2

10:1

Hey Hot Rod, 10:1 would be totally ideal. And boiler sizing would be very simple and allow big steps between sizes.