Another tankless water heater replacing boiler thread

[OurTown]

I'm considering using an additional temperature controller instead of the Weep Mizer's output 2 because it looks like it has only a 1 degree differential. Correct me if I'm wrong.

 

[OurTown]

This is the temp sensor I was considering buying two of for both primary and secondary pump circuits.

https://www.supplyhouse.com/Johnson...perature-Control-w-19-1-2-Leads-120-240V-SPDT

 

[Randy]

There's one on Amazon that looks pretty interesting
bayite AC 110V Fahrenheit Digital Temperature Controller 10A 1 Relay with NTC 10K Sensor Probe

 

[OurTown]

There's one on Amazon that looks pretty interesting
bayite AC 110V Fahrenheit Digital Temperature Controller 10A 1 Relay with NTC 10K Sensor Probe

I have used that one before for a non-car wash project but they are made to mount in a panel.

 

[2Biz]

I'm back on this project. Are you saying that if using two heaters the two pumps should be in series and then split off to each heater inlet? Or do you think there needs to be two pumps per heater? I'm still trying to figure out pump sizing on the primary loop.

I don't know that you would need 4 pumps (2each in series). 90% of the time, only one heater will run. Even if both heaters run, you'd only be looking at about 12-13 gpm...(2) 013 Tacos in series will deliver 30gpm at 40psi....I get about 6.0gpm with one heater at 40 psi...It flucuates a few tenths of a gpm based on how cold or warm the inlet temp glycol is....

 

[2Biz]

If I use the old buffer tank and run it vented on top will I need a larger pump to circulate the secondary loop? Will this introduce oxygen into the system? It was vented before and used a cast iron pump, but that does not necessarily mean it is okay. I should not need an air eliminator or an expansion tank, correct?

If you run the buffer tank and its vented AND if you run a trough loop. The tank will over flow....And yes, it will allow oxygen into the system. I run mine closed loop...Never had a problem, knock on wood! I don't think the size main loops circulator would make a differnece either way. If you run it open, you don't need an air eliminator or Expansion tank...The buffer tank is the air eliminator and Exp Tank! LOL

 

[2Biz]

I'm considering using an additional temperature controller instead of the Weep Mizer's output 2 because it looks like it has only a 1 degree differential. Correct me if I'm wrong.

Why....When it gets cold out, temp is coming down and usually goes past setpoint....Slabs already warmer from the higher temps of the day. I control my floor heat pumps from output 2...Never have seen it short cycle...I have output 2 set at 32°....Using a different controller and The larger diffferential you set will keep it on longer than necessary that wastes energy. If the temp is rising, why would you want it staying on at 33° or more after the slabs are already warm? I'm sure you are already aware, but you need to make sure you have a relay big enough to handle the load of all your pumps. Use output 2 to control that relay...I'm sure the bayite controller will work though. I have several of them controlling various things...Coin Box heaters, Pop machine heaters, Attic fan ventilators at home, etc....They are a great little temp controllers that doesn't break the bank @ $20 each!...

 

[OurTown]

Why....When it gets cold out, temp is coming down and usually goes past setpoint....Slabs already warmer from the higher temps of the day. I control my floor heat pumps from output 2...Never have seen it short cycle...I have output 2 set at 32°....Using a different controller and The larger diffferential you set will keep it on longer than necessary that wastes energy. If the temp is rising, why would you want it staying on at 33° or more after the slabs are already warm? I'm sure you are already aware, but you need to make sure you have a relay big enough to handle the load of all your pumps. Use output 2 to control that relay...I'm sure the bayite controller will work though. I have several of them controlling various things...Coin Box heaters, Pop machine heaters, Attic fan ventilators at home, etc....They are a great little temp controllers that doesn't break the bank @ $20 each!...

So you only have one relay? How do you run the secondary loop pump separately from the primary? The primary loop has an aquastat that controls those pumps, correct?

 

[OurTown]

I'm thinking of three relays. Relay 1 would control the secondary loop pump when it gets below freezing. Relay 2 would control primary loop pump. Relay 3 would have the coil wired from output of relay 1 and the output contacts go to supply power to relay 2 contact. I'm probably not explaining it well but it works in my head. That way the primary pump would never run if it is above freezing outside.

 

[2Biz]

So you only have one relay? How do you run the secondary loop pump separately from the primary? The primary loop has an aquastat that controls those pumps, correct?

Yes, only 1 relay. The relay turns on the main bay loop circulator at 32° and also powers the heater pumps....BUT, those pumps are triggered on/off by the return glycol temperature aquastat....The aquastat is wired between the relay and the heater pumps. Once temp rises above 32°, the whole system is turned off.

 

[2Biz]

I'm thinking of three relays. Relay 1 would control the secondary loop pump when it gets below freezing. Relay 2 would control primary loop pump. Relay 3 would have the coil wired from output of relay 1 and the output contacts go to supply power to relay 2 contact. I'm probably not explaining it well but it works in my head. That way the primary pump would never run if it is above freezing outside.

You are over thinking it. Too many relays! Apply the KISS method! LOL

 

[OurTown]

Yes, only 1 relay. The relay turns on the main bay loop circulator at 32° and also powers the heater pumps....BUT, those pumps are triggered on/off by the return glycol temperature aquastat....The aquastat is wired between the relay and the heater pumps. Once temp rises above 32°, the whole system is turned off.

So are you running the full primary loop pumps' load through the auquastat?

 

[2Biz]

So are you running the full primary loop pumps' load through the auquastat?

Yes, the contacts in the Aquastat have a 20a rating! The Taco 013 pumps are only 2a each, total 4a load on the aquastat.....

 

[OurTown]

Yes, the contacts in the Aquastat have a 20a rating! The Taco 013 pumps are only 2a each, total 4a load on the aquastat.....

The stats that I'm looking at have 16 amp rating so I should be good there. If I used two of them, one for return temp and one for outdoor then I probably don't need any relays. All three pumps' 6 amp load would run through the outdoor stat and 4 amps through the one used for aquastat.

 

[2Biz]

The stats that I'm looking at have 16 amp rating so I should be good there. If I used two of them, one for return temp and one for outdoor then I probably don't need any relays. All three pumps' 6 amp load would run through the outdoor stat and 4 amps through the one used for aquastat.

Question, Why the outdoor stat? I only run off the return aquastat....I use the secondary output off the weepmiser for outdoor temp that energizes the single relay for the floor heat system. I have never had any issues doing it this way.

 

[OurTown]

Question, Why the outdoor stat? I only run off the return aquastat....I use the secondary output off the weepmiser for outdoor temp.

The wire run from the Weep Mizer is going to be about 40'. I think a 2 degree differential might be better on those 32 degree days. I guess setting output 2 at 34 (not sure if that's the HL or LL) degrees may accomplish similar results though. Our old system had only one pump and it ran all winter so this is a major improvement. My idea, if it works, would eliminate running extra wires, a junction box and a relay. Crazy simple. I need to get this installed this week. If I were to use the Weep Mizer what do you have your HL and LL set at?

 

[2Biz]

The wire run from the Weep Mizer is going to be about 40'. I think a 2 degree differential might be better on those 32 degree days. I guess setting output 2 at 34 (not sure if that's the HL or LL) degrees may accomplish similar results though. Our old system had only one pump and it ran all winter so this is a major improvement. My idea, if it works, would eliminate running extra wires, a junction box and a relay. Crazy simple. I need to get this installed this week. If I were to use the Weep Mizer what do you have your HL and LL set at?

I have my secondary output coming on at 32°... I copied this from the manual:

OUTPUT 2 OPERATION Output 2 is designed to be an on-off switch. This output is programmed using the LL and HL settings in the programming section. If the temperature is between the LL and HL settings, the output will be OFF. If the temperature is 1° below the LL setting or 1° above the HL setting the output will turn ON and remain on until the temperature rises to 1° above the LL setting or falls to 1° below the HL setting. Should you wish to control output 2 based on a temperature other than the outside temperature, connect a sensor in the number 3 sensor position. Output 2 will then operate using the temperature from that sensor. Output 1 will continue to operate on the outside temperature.

So given this, I have my LL set at 33° so it turns on at 32°. HL is set at default 113° so it does not turn on above 33°. The HL is for a cooling mode situation. FWIW...I have both the main loop circulator and heater circulators turn on/off using a light switch so I can micro manage if I want. My bay floors will not freeze down to about 25° depending on daytime temps. So why have the system run on those days? Basically if you read this correctly, you have a 2° differential with the LL setting!

 

[OurTown]

I have my secondary output coming on at 32°... I copied this from the manual:

OUTPUT 2 OPERATION Output 2 is designed to be an on-off switch. This output is programmed using the LL and HL settings in the programming section. If the temperature is between the LL and HL settings, the output will be OFF. If the temperature is 1° below the LL setting or 1° above the HL setting the output will turn ON and remain on until the temperature rises to 1° above the LL setting or falls to 1° below the HL setting. Should you wish to control output 2 based on a temperature other than the outside temperature, connect a sensor in the number 3 sensor position. Output 2 will then operate using the temperature from that sensor. Output 1 will continue to operate on the outside temperature.

So given this, I have my LL set at 33° so it turns on at 32°. HL is set at default 113° so it does not turn on above 33°. The HL is for a cooling mode situation. FWIW...I have both the main loop circulator and heater circulators turn on/off using a light switch so I can micro manage if I want. My bay floors will not freeze down to about 25° depending on daytime temps. So why have the system run on those days? Basically if you read this correctly, you have a 2° differential with the LL setting!

Still sounds like 1 degree to me. If LL is set to 33 then it turns on at 32 and stays on until it reaches 33 or higher again.

 

[cbchevy4x4]

Still sounds like 1 degree to me. If LL is set to 33 then it turns on at 32 and stays on until it reaches 33 or higher again.

Its 2 degrees, If LL is set to 33 then it turns on at 32 and stays on until it is higher than 33(34), not 33 or higher.

 

[2Biz]

Still sounds like 1 degree to me. If LL is set to 33 then it turns on at 32 and stays on until it reaches 33 or higher again.

Are you playin' with me?!

"If the temperature is 1° below the LL setting it will remain on until the temperature rises to 1° above the LL setting"

Edited to take out the HL stuff....CBChevy said it...If setpoint is 33°, It comes on at 32° and turns back off at 1° above LL which is 34°, a 2° diferential!