Tankless Boiler/water heater combo

dnevistich

Hello,

I need a new boiler, I have a closed loop hot water radiator system. I was thinking of going with a tankless boiler/water heater combo to save space and increase overall efficiency. Can someone recommend a good one. I have a 2100sq ft house with 2.5 baths. Also, someone mentioned that the boiler does not get the water hot enough sometimes for the boiler to be sufficient to circulate through the whole entire loop. Any insight would be helpful.

Thank you

Rich_49

Do you currently have a boiler and separate water heater ? Have you entertained the thought of having a heat loss and blower door performed to figure out what you actually need in the way of boiler sizing ? These 2 steps are the very first steps you should take .

aircooled81

is thereanklee a piping diagram for tankless heaters used for hydronic heating loops?
I have seen when closing the loop, like a resirc pump on a tankless heater starts to gain expansion problems, and has typically needed a storage tank. Plus returning hot water complicates the tankless water heaters firing range. you'd need to bring the water up from cold, then coast it at a low fire while trying to keep the loops set point.
basically, does a tankless heater really utilize less space for hydronic heating?

wcs5050

Combi units are good for mechanical rooms of minimal size. Rinnai has an nice lineup of these that perform well. However, since combis utilize flat plate heat exchangers for domestic hot water, for the most part, they require cleaning/flushing in addition to burner maintenance. If there is room, a high efficiency boiler in connection with an indirect water heater is a better, lower maintenance installation. As to "someone's" comment about losing temperature through the loop, there are many factors affecting that. First thing to do is have a heat loss calculation done on the home so the new boiler is properly sized.

Snowmelt

Navien has a good unit, where are you located?