check valves on dedicated snowmelt

Tinman

What are your thoughts on the use of flow check valves for a dedicated snowmelt, 1 zone, piped primary secondary?

I'm struggling to see the need. The two pumps are hydraulically separated from one another and if there is any thermal migration, it won't be an issue for long especially if the boiler is in a space that's kept at 35 degrees.

icesailor

Have you ever looked at the flow charts for say a Taco 007 and the GPM's put out with and without IFC's? If flow is an issue, and it is a dedicated boiler to snow melt, why would you need it, and why would you need to add all that extra resistance to the piping.

Or, install a Zone Valve. A motorized check valve. Just to shut people up.

IMO.

Tinman

My point exactly...just looking for verification because someone I respect disagrees. I won't be installing a zone valve. I'll stand on principle and physics.

hot_rod

Are the boiler and melt pump tied to run together? If it just one zone, does the primary ever run without the secondary?

Does the boiler maintain temperature, or just fire on a melt call?

For sure you need check protection on both S&R when the boiler is below the distribution and the secondaries rise vertically from the primary loop, in heating applications where the boiler maintains a loop temperature.

Tinman

Not all the time. There would be times when just the secondary (system) pump would be running. The primary won't run w/o the secondary.

Boiler runs only on a call for "Melt".

If we're hydraulically separated (while running) and the temperature differences are going to equal out very quickly during the off-cycle, why would they be needed? Is it because of the few times that the secondary pump is running w/o the primary?

Tinman

I typically would use a Tekmar 654 which requires two external relays. One to bang on the boiler and primary pump and one to bang on the secondary pump.

Mark Eatherton

If the boiler is ONLY doing snowmelt, and no possibility of doing another load (like DHW or hot tub) then no Czech's required.

But if it is eventually going to be doing another load, then Czech it.

Also, the boiler must be freeze protected with the same glycol going through the slab. Otherwise you could get into a forward thermo siphon condition that can freeze and break plate or tube heat exchangers.

If none of these conditions apply, then no Czhechs :-)

Which brings to mind a joke. A Pol, a Russian and Czech went bear hunting in Jellystone National Park.

They checked in with the rangers, but never checked out. Upon inspection by concerned rangers, the found that all three men were killed in a bear attack, and eaten by the bears.

The rangers found the marauding bears still in their camp (male and a female) and dispatched them. They performed a necropsy on the bears, the female first because she had the biggest belly. Upon opening the female, they found the remains of the Russky and the Pol. Ranger one looks at ranger two and says "Well then, the Czech is in the male..." (I've used this before with suppliers I owed money to)

Hold your applause, I am here all week. Be sure and tip your wait staff :-)

ME

icesailor

Poor bears.

They have to eat too you know.

Tinman

No Czance of adding an additional load. : ) Zero.

I appreciate you confirming my sneaky suspicion.

And yes, same glycol running through the slab will be running through the boiler.

I'm keeping that joked tucked away should I ever need to use it.