tapping the steam boiler high for indirect hot water

Jack M

Expensive bronze circulator pumps are often used on steam boilers with indirect hot water heaters.
Richard Trethewey of Ask This Old House TV demonstrated how to install an indirect and placed the boiler tap for the circulator pump high up on the boiler near the water line, "to avoid drawing crud from the base of the boiler."
Is this recommended location? Looks like an less expensive circulator (not bronze) was used. Can you get away with a cheaper pump if you tap high enough? Trethewey placed a Y-strainer after the ball valve to act as a filter and flush point.



https://thisoldhouse.com/how-to/how-to-install-indirect-water-heater-boiler

Jamie Hall

Well... yes, it would avoid drawing crud from the bottom of the boiler. I can see that. Assuming you have that much crud in there. But it wouldn't address potential corrosion problems -- that's related to water chemistry, not crud. I'd still want a bronze circulator. And I'd want to be darn sure that the intake was well below the low water cutoff on the boiler.

jumper

Too bad nobody makes a small steam fired water heater. AERCO ones were successful on larger projects. No pumps & no traps needed.

Jack M

Nice. I did not know about these steam fired domestic hot water systems. I guess you would install the hot water heater above the boiler (if you didn't want a pump) to allow the condensate to gravity flow back down to the boiler. But where is the steam valve?
The commercial units are still made and turn up at on-line auction sites.




aerco.com/product/bii-waterwizard

EBEBRATT-Ed

If your pumping steam boiler water a bronze pump is best. But don't use a water lubricated pump under any circumstances.

A three piece pump like a taco 110 or a B& g 100 CI pump will work but won't last as long as bronze

MilanD

Question (as to the TOH video): I can see this is a great way to get domestic hot water in the winter. Unless it's system steam running year-round, isn't this indirect domestic water heating a bit wasteful in the summer?

Plus wear and tear on the steamer, pumps, esp. when using oil - the burners. Then, burning oil to heat water in the summer, indirectly, on a CI boiler one must get the water in the steamer to at least 140*F for flue gasses not to condense ... Wouldn't a nice electric dhw heater just do the trick year-round, or get one for use in the summer? My gas dwh comes out at 120*F. Plenty hot and no worries about scalding. Replace the anode rod every 5 years for 20 bucks, the thing will last a long time.

I'm assuming there is no natural gas available, thus the electric dhw heater. Same for nat gas.

Jack M

It might not be wasteful ($), given oil and electric prices and depending on the length of the heating season. I'm in New England and run the boiler into the shoulder season of May and June, then we start up again with cold mornings in September. That leaves July and August. Oil is currently $2/gallon and electricity is 7.7 cents per kwh. Using this calculator and a 70 % efficiency (for oil) there's not much difference in cost (a $500 utility rebate on oil fired indirects). Continuing to run the boiler during the summer months perhaps prolongs it's life by keeping everything moving.

Then again, there's a great domestic hot water analysis here that makes Hybrid electric systems attractive:

smarterhouse.org/water-heating/replacing-your-water-heater

BobC

Did you include transmission and any fees with that cost of electricity?

I'm just south of Boston and paying 20.4 cents per KWH and that is after shopping for the best deal on energy suppliers available to me (I'm paying 8.9 cents for electric supply). My cost for NG is about $1.36 per therm.

This demonstrates how badly screwed were were by deregulation, they can charge anything they want for distribution and not bother with the generation of power. What deregulation did was to double the number of CEO's with all the admin costs that entails - aren't we lucky to be so blessed

Bob

Jack M

BobC , no I did not add in the distribution and transmission fees. with those added the cost per KWH jumps up to 20 cents. The electric water heater option (even the hybrid) starts looking less and less attractive.

BobC

@Jack M i thought that might be the case; I wanted to make sure you were comparing the total costs so you wouldn't get blindsided.

Bob

MilanD

Thank you gents. The charts are great! We heat for about 6 months here in Cincinnati, and use natural gas. Can't get away from fuel riders. I need to take a look at total cost per ccf with riders and all - it's about $.65 or so...

MilanD

I stand corrected, closer to $0.70 per CCF, and it fluctuates thereabout, more on colder months, less on warmer months.

Wait, so our nat gas here is about 60% cost of yours up north-east at $7 for MCF? Here I was thinking we are still getting ripped off... do add another $1/day for gas meter - we are charged $33.50/month to have a gas meter aka. "Fixed Delivery Service Charge" on residential.

On commercial bldng, small user between 5-10k CCFs/year of use, monthly Fixed Delivery Service Charge is $226.64 regardless of use. Add that to a average 900 CCFs of monthly use over 6 months, brings the cost of CCF to $0.95 for commercial use.