can you add on demand to an older gas boiler for radiant baseboard heat?

beoutside

We have an older system in a small house. It is a Valliant boiler closed-loop radiant floor baseboard with the individual on/off valves at each heater. Is there a way to add on-demand hot water?
Thank You
Donny McClure
Carpenter/ home Plummer and mechanic

Zman

Does the boiler have a plate where a tankless coil could be installed? Pictures?

beoutside

No, just the gas and water in on the back, flush on the front bottom. We are demoing the pantry and looking to save space and thinking of replacing the electric water heater that is as old as I am.
Thank You

HVACNUT

Add an indirect water heater with priority.

GroundUp

"On demand" is going to cause a lot of short cycling for the poor boiler on short bursts of hot water just for hand washing or whatever. It can be done but I would go the indirect route like has been mentioned above so you have some storage

Zman

As mentioned, a small indirect (30 or 40 gallon) would be a good option.
I think we need to talk about your flue pipe. Is that what I think it is? A closer picture would help.

HVACNUT

> @Zman said:
> I think we need to talk about your flue pipe. Is that what I think it is? A closer picture would help.

Looks like Z-Flex, Zman. Would've been a straight shot up and in with 26 gauge gal pipe. Lazy.

beoutside

Yes , that is the way it was vented when we bought the house. Flex pipe to an old chimney.

beoutside

Appreciate all the input, this old house did a video on adding an indirect with all the correct valves and safety measures..... I guess we can bypass saving space and just put the indirect were the old water heater is. On the video, the broiler used was larger than ours and had a side plate accessing the water they used to heat the house. With our baseboard radiant system, it is much smaller heating baseboard heaters, approx 40 feet total on one floor. We also heat with an efficient airtight wood stove.

beoutside

Ill double check but think our boilers BTU's is only 50000. Someone online recommended a minimum of 100000 for it to pump out hot water at an acceptable and predictable rate. Is that the case? Maybe we should just ad a tankless hot water system?

beoutside

Do you need 100000 Btus an indirect system to work well?

Zman

Your existing electric heater is probably 16,000 btu. Your 100,000 is probably derated to 80,000 btu. An indirect should do the trick

beoutside

Does your broiler need to pump out a minimum of 100000 Btus, I meant!

beoutside

I’ll check but I think our broiler is 60000 BtU and I hear you need 100000 btu broiler as a minimum ? To work with an indirect

GroundUp

Aren't broilers used in the kitchen? According to the ID tag photo above, your boiler's output is 50k which is plenty for your DHW needs when on priority. You won't get any space heating while on a DHW call, but that's not typically an issue unless you plan on using a million gallons of hot water

beoutside

Thank you ! I’ll broil you up some rib eyes

GroundUp

beoutside said:

Thank you ! I’ll broil you up some rib eyes

Medium rare please