Navien 240A navicirc throws hot water into cold line

[Kdaadm]

Hello, I am planning to have Navien 240A tankless heater with Navicirc valve installed to get hot water quickly.
1. I am told that the navicirc crossover valve does not really make so much difference to get hot water quickly. Is that true? Can anyone give feed back on Navicirc performance ?
2. Also I heard there is a greater chance of getting hotwater from the cold water line in the faucets that are more close to navicirc crossover valve. Is that true ?
3. The check valve suggested to be put in the cold water inlet line above the recirculation line Tee in the cold water line is going to restrict the cold water flow and reduces the quantity of the hot water out flow. Is that true?
4. I have 1/2 inch natural gas line (high pressure though) connecting to the present 50 gallon tank water heater. If I change to Navien 240A should I get the gas line changed to 3/4" dia ?
Please suggest, Thanks in advance.

 

[Bannerman]

1) While the hot water exiting the WH may be considerably hotter, the thermostatically controlled valve within the NaviCirc will block circulation once the NaviCirc valve senses 95 degrees F. This will prevent cold water supply lines from becoming too hot since the NaviCirc utilizes the home's cold water piping to act as the recirculation return line back to the WH. With the 95-degree limit, warm-hot water will arrive at hot faucets more rapidly, but when the WH temperature setting is greater than 95-degrees, the temperature will further rise as additional hot water is utilized.

When a dedicated recirculation return line is utilized, no NaviCirc valve will be needed and there will be no reason to limit the temperature of the return piping so full temperature hot water will arrive at faucets more rapidly.

2) Coldwater faucets and toilets located nearby to the NaviCirc will typically flow warm water (<95-degrees) until further cold water use causes the warm water within the cold lines to be replaced with cold water.

3) Not true. Water to supply the WH will enter through 2-routes including both the Domestic Supply inlet and the Recirculation Water Supply Inlet. The purpose of the check valve located within the Domestic Supply line is to prevent reverse flow through the Domestic Supply to the Recirculation Water Supply inlet while the recirculation pump is operating..

4) The diameter of the gas piping required, will be conditional on various factors including the equivalent piping distance the WH is located from the pressure regulator at the gas meter, and the connection order of other gas-burning appliances within your home. See gas supply requirements detailed as starting in section 3.3 of the NPE Installation & Operation Manual linked below.

Navien NPE Installation & Operation Manual

Check also that the existing Gas meter and pressure regulator will support the increased gas flow requirements for your entire home.

 

[Sponsor]

 

[Kdaadm]

Thankyou so much for the clarifications given. Greatly appreciate your help 'Bannerman'

 

[Kdaadm]

Couple of questions:
1) While the Navien recirculating pump is ON and the Navicirc valve is allowing hot water to flow in to the cold line is it possible that the hotwater is pushed back into the municipal line (especially if the Navicirc valve is located farther from the water heater but more close to the municipal cold water line).
2) After reaching +95 deg temparature at the inlet side of the navicirc value when it cuts off the flow into cold water line, the recirculating pump in the Navien heater would still be running pressuring the hotwater line, right ? How would the pump know when to stop to avoid this situation. How do the navicirc valve and the built-in recirculating pump coordinate and work together ?

Thanks in advance for all the experience shared.

 

[John Gayewski]

There is no pressure build up. They don't build pressure they aren't actually pumps. They circulate. Like a ceiling fan throws air around a room it doesn't create pressure just velocity. There is a pressure increase when a circulator runs that is a side effect of throwing the water. It's not good for the pump but they are built to run that way.

It's certainly possibly hot water could go into the water supply but very unlikely. There's no draw from the water supply. A circulator runs like a ferris wheel it pulls and pushes at the exact same time. It can't really pull the from water supply.

 

[Kdaadm]

Thankyou John