Weep Water + On Demand Heater

[Bubbles Galore]

I am working on removing my storage tank and 20 year old boiler and replacing it with an on-demand Takagi (I am using one for my pre-soak in the automatic and it works fantastic!). Do any of you have experience with weeping hot water while using only an on demand system? I don't know if it will even be an issue, but I know with the way the water is cycled and the frequency, it may force the heater to run more than normal. Am I overly concerned or could this be an issue?

Thanks!

 

[pitzerwm]

If you want hot water weep, get a small separate heater just for that. Mine was set up that way, but I never saw the need to weep hot water. Maybe plumb a small insulated tank into the system and when it got low or cool, use a small pump to run it through the heater.

 

[bigleo48]

Bubbles,

As you know, tankless units operate on flow (mine are about 1/2 gallon/min to fire). That's not much and I have 8 SS bays.

As you also know, the only reason to weep hot water is to weep less than cold water. So you may not need to. I use the second set of contacts on my weepmiser to toggle a 3way solenoid between hot and cold weep at a certain temp. At that point I am weeping constantly and my floor heating (which is also off my tankless) is running constantly, so quick cycling the units is not a problem.

Another very important thing to do, is to disable the flow restrictor on you tankless units. These valves will restrict flow to maintain water temp. This can starve your system, including your SS pumps if you heat water with the tankless units. In my Rinnais, its a matter of unplugging them when I know they are fully open.

Big

 

[Bubbles Galore]

Bubbles,

As you know, tankless units operate on flow (mine are about 1/2 gallon/min to fire). That's not much and I have 8 SS bays.

As you also know, the only reason to weep hot water is to weep less than cold water. So you may not need to. I use the second set of contacts on my weepmiser to toggle a 3way solenoid between hot and cold weep at a certain temp. At that point I am weeping constantly and my floor heating (which is also off my tankless) is running constantly, so quick cycling the units is not a problem.

Another very important thing to do, is to disable the flow restrictor on you tankless units. These valves will restrict flow to maintain water temp. This can starve your system, including your SS pumps if you heat water with the tankless units. In my Rinnais, its a matter of unplugging them when I know they are fully open.

Big

Do you operate your floor heat as a non-pressurized system?

 

[bigleo48]

Do you operate your floor heat as a non-pressurized system?

Nope... pressurized.

 

[JIMT]

Another very important thing to do, is to disable the flow restrictor on you tankless units. These valves will restrict flow to maintain water temp. This can starve your system, including your SS pumps if you heat water with the tankless units. In my Rinnais, its a matter of unplugging them when I know they are fully open.

Bigleo,
I just install a Rinnais for hot water. Is the flow control valve located at the bottom of the heater just above the hot water outlet. If it is it has 6 or so wires in the wiring connector.
Is that what you disconnected? I was afraid to disconnect it.

Thanks,
JIMT

 

[bigleo48]

I just install a Rinnais for hot water. Is the flow control valve located at the bottom of the heater just above the hot water outlet. If it is it has 6 or so wires in the wiring connector.
Is that what you disconnected? I was afraid to disconnect it.

Thanks,
JIMT

Jim,

Depends on the Rinnai, but I think your correct. Your manual should point it out also.

Disconnect it and see. The worst its gonna do is give you and error code.