some splaining please, Lucy

Gimpy Greg

While standing by I shot the deputy from the bell tower.

Gimpy Greg

steam vs. HW

I am just an innocent bystander learning as I read here.
I understand the use of heat loss calcs for HW. BTU in to
cover the BTU out. I even watched engineers do them the old way with a pencil and paper, first time I ever heard of
ASHRAE.I can also understand matching a steam boiler to the
radiation. But when you do a steam boiler replace and count the sections and match the boiler, how do you know how much
the boiler is oversized ? If it were undersized you would
be doing more than just a boiler replacement (maybe adding or moving radiators)Is it a matter of Cost? If it is too big the customer knows he is warm and doesn't want to pay to have his radiators reduced or removed to get a slightly
smaller boiler. How and why do you guys do what you do ?
Do you trust that the Dead Men put in the right amount of radiation and the existing boiler is correctly sized for
heat loss, I realize it should match radiation. It just
seems to me that there is a great potential for steam
boilers being oversized since heat loss seems to be mentioned regarding hot water but not steam. Please set
my thinking straight, but realize you can't straighten
out the hunch back of Notre Dame !
Regards,
Greg

Brad White_28

Excellent questions, Greg

Here is my perspective from the design-side of things. How the operation and maintenence aspects are affected in detail I will leave to the greater minds and hands on this site:

You are correct in sizing steam to the connected radiation but my practice is to ALSO perform a heat loss calculation and reconcile the two.

If the heat loss is significantly less than the radiation output the only solution to avoid short cycling or having an over-sized boiler is to remove (not add) radiation.

The dead men had several methods to "calculate" heat loss. Early on these were empirical, "what worked before was applied again", regardless of if it could have been less and still worked. In Dan Holohan's Lost Art of Steam Heating and sequel book, there is so much in so many areas to explain this in much more detail. Suffice it to say, they the dead-men knew, even without knowing, how to heat. Oversizing was the rule of the day by default. Fuel was perhaps less expensive in proportion. And aside from cholera, typhoid and influenza, life was good.

To sizing: Say you have an old Victorian with an uninsulated heat loss in the range of 60-65 BTUH per SF (of floor area). Your radiation may in fact support a heat loss of 80 to 100 BTUH/SF. How do you know? Without calculating, you don't.

So you calculate a heat loss and find you were right, you have 65 BTUH/SF loss and radiation (and boiler) to heat 100.

Now you insulate, replace windows, add storm windows, caulk, re-side, wrap in Tyvek and your calculated -and actual- heat loss drops to the 35-40 BTU/SF range. Your boiler and radiation are now 2.5 times the size they needed to be. Huge gulps of fuel, race to heat the house, then a coffee break for the boiler. Cycle City.

So your job as a competing contractor is to convince the homeowner with facts (some cheery emotion acceptable) that they will save money by down-sizing the system and removing radiators from the boiler load. The boiler sizing method is still the same, it just has to be more in proportion to the heat loss, especially the improved one.

Hope this helps straighten you out. I have the name of a good Chiropractor if it does not.

Brad

Brad White_9

Meant to add in the 3rd. Paragraph

"If the heat loss is significantly less than the radiation output the only solution to avoid short cycling or having an over-sized boiler is to remove (not add) radiation..

>INSERT> AND have a properly sized boiler matched to the actual radiation.

Bob Morrison_3

Calc the load each time you do a project...

Greg,

I echo Brad's remarks: regardless of new or existing conditons- steam, hot water or electric plant- do the best possible heat loss calculation. Everything starts with the load. An expected load in the times of dead men (when windows were double-hung, etc) is not the same as one now. Don't assume that anyone (live or dead) is correct; always do your own estimate.

Bob Morrison

jerry scharf_3

National Lampoon

In the mid 70s, one issue of National Lampoon and a small filler article on on page. This is all it said.

"A National Lampoon survey has discovered that over 70% of all bystanders are not innocent."

I think of it every time someone mentions innocent bystander.

jerry