Domestic coil on steam boiler

Snowmelt

I seen every once in a while I seen a domestic coil on the steam boiler used for an indirect water or a zone, for a water zone on an added addition makes sense but water about for an indirect water heater? Wouldn’t that be counterproductive, or a smart move ?
follow up question I know the coil has 3/4 connections, if you increase to one inch and use a 009 or a 26-99 pump would that be a good start to have the proper GPM for hot water…

EBEBRATT-Ed

Indirects already have a coil in them so no need for two coils. If you used both coils you would need a circ, expansion tank air vents and prv water mu and relief valve. You can use a tankless coil with an electric water heater tank or an aqua bank (tank with no coil).

EdTheHeaterMan

@EBEBRATT-Ed has a good point. If you use the boiler water in the indirect water heater coil HX, all you need is the pump for an open system. I have used a tankless coil on a steamer to add a small baseboard HW zone to an otherwise huge boiler for that small space. A church with over 10,000 sq ft of floor space. The restrooms, the secretaries office and the pastor's office were heated by steam when I bid the new boiler. I offered the option to heat the 4 small rooms with their own hot water zone, so now you don't need to send steam to the entire building to get heat on any given weekday when only those small rooms are occupied.

This involved making the tankless coil a part of a closed system with a circulator, expansion tank and relief valve as if that coil was a regular boiler. The steamer will heat the water around the coil without making steam with a limit control set at 170°F.  I felt that was a better system since the baseboard radiators were going to be above the boiler’s water line.  More dependable and less knowledge needed to keep the baseboard full of water, compared to an open system boiler water running through the baseboard loop.   

In your situation when the indirect water heater HX is lower than the boiler’s water line you can very easily use the boiler water to heat the tank without the extra closed system parts required with the tankless coil as the heat source.    

Snowmelt

ed that a was referring to, do a set up like that instead of using the add a loop method …add near boiler piping like a traditional boiler..

Snowmelt

ed the heating man, I understand the theory completely so if you did a indirect water heater you would just use the add a loop method since it was low and right at the boiler

Snowmelt