Am I doing my old boiler a disservice

[stefan66]

I'm currently running an old "Franks Piping" boiler
1000 gallons unpressurized storage
Homemade heat exchangers in top and bottom of tank
Radiant in-floor heat is the only load
Today is 10F outside
3 gallons\min. of 91Deg. water req. to keep house at 74deg.
Is it alright to send water out of my boiler at 130 degrees?
All I need to satisfy my load till the next firing is around 110deg..
Read so much on here about boiler return temp protection.
Am using a mixing valve for near boiler circulation.
Water temp entering boiler at 120 exit at 130
Sound alright?

 

[webbie]

Well, if that thing has already lasted that long, I doubt you will do it much harm now. Some boilers are actually rated for low temp operation, but in your case I would not worry too much about it because your machine is on (generally) borrowed time anyway!

However, if one buys a new boiler these days, you should consult with the manufacturer about the suggested operating temps. If the boiler does not allow low temp water, then 140 is usually about the lower end.

 

[ISeeDeadBTUs]

I'm confused . . . isn't the boiler circulating through the HX in the bottom of your storage? If so, why would you not run the boiler at 180 °F ?

 

[nate379]

What kind of boiler. A non condensing one needs to be min 135* and up, all depending on construction (most are cast iron heat Xchange)

Condensing will have a non rusting material, stanless, etc and they can go no min temp.

 

[stefan66]

I'm confused . . . isn't the boiler circulating through the HX in the bottom of your storage? If so, why would you not run the boiler at 180 °F ?

The old boiler can't keep up when dumping that much heat
The best it can do is to keep itself about 30deg.F. above storage temp. even with the mixing valve wide open.
I've never seen a smaller boiler

 

[stefan66]

What kind of boiler. A non condensing one needs to be min 135* and up, all depending on construction (most are cast iron heat Xchange)

Condensing will have a non rusting material, stanless, etc and they can go no min temp.

This boiler is basically 1/4'' steel all around.
Definitely not condensing, way too old.
It was a freebee from an old friend who used it for five years and then it sat in his basement taking up space till I saw it (20 years later).