gravity system conversion

[furiousman]

I have an oil-fired, open gravity hot water system and would like to convert to a natural gas fired boiler, but unsure how to make this work efficiently. There is no separate hot water heater. everything is tapped into the gravity system! Hot water taps, inclluding the baths all tap into the gravity system. I am told to do the following:

-add a B&G pump (on the "hot" supply side) to add forced circulation.
-reduce pipe diameter on near boiler piping (to increase resistance for pump)
-Remove expansion tank and add compression tank
-add a bypass loop with mixing valve to preheat cold return as not to induce thermal shock in boiler.

But a couple of things bothers me.

In the summer months, to get hot water, I need to run the boiler. Noting the large volume of water to be heated, this is inefficient. How do I make this a more efficient process?

do I bother insulating the large diameter copper tubes that loop around the house?

Is there a way to get hot water where I need it without heating a massive volume of water?

Is it worth adding a highly-insulated hot water tank as a thermal reservoir?

Should i add two hot water boilers? One for the supply and one for the return?

In all, would love to know how to make my current system more efficient without tearing out the entire system.

 

[pekasus]

As far as I know, you can't make these type of heaters efficient for hot water only. Since the problem only arises in the summer months, why not install a solar? You could do an entire solar heating system, or just install a single panel to preheat the water, then install small point of use heaters to add 40 degrees.

Modifying your system would still make it cycle often throughout the summer, adding wear to the unit.

 

[furiousman]

OK new problem.

Got a home with 1940s vintage oil fired steel boiler (btw it's massive!) feeding a 1 1/4" monoflow system supply 19 Arco concealed cast iron convectors.

going to replace boiler with a buderus G215/4 with riello oil burner.

Issue: heating zones:

Late 1970s, owner built a 23'x15' family room extension and installed hot water baseboard. Plumber added baseboard circuit by tapping into supply side of boiler, before monoflow supply valve.

family room has one thermostat (baseboard), the other thermostat in dining room (convector).

Problem is the boiler runs all the time because of baseboard cooling down so quickly, but the rest of the house is scorching even with the dining room thermostat at 60!

how do I solve this uneven heating problem? Do I remove baseboard and add cast iron convectors? do I throttle back each convector on the monoflow loop?

 

[johnjh2o]

Are the two systems on separate zones? You can not mix cast iron radiation with copper fin baseboard. If they are on separate than a picture of the boiler and the piping will be necessary to be able to help you.

John

 

[furiousman]

The baseboard and monoflo are two separate zones.

 

[johnjh2o]

I don't see a flow check on either the baseboard zone or the monoflo zone. With out these the system will gravity feed as long as there is temperature in the boiler.

John