No zone valves on my system

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bentz69

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I have oil heat with 3 zones/3 thermostats (basement, 1st/2nd floor) using baseboards. The 3 thermostats are 110v line voltage units that operate the 3 circulator pumps. There are no zone valves on this system. I would like to install 3 Nest thermostats to replace these old line voltage units.

My plan is to install three 3 zone valves. I will re-use the current wiring (no plans on running new wires through the walls) to give the Nest's the 24v it needs by having the power supplied by a transformer. The Nest's will operate the zone valves and I will wire the micro switches in the zone valve to the circulator pumps to supply the pumps 110v to operate. Ive seen several systems that use the Nest which don't have a dedicated C wire and they work fine with no power lose over long term periods of non-usage.

Looking for input. Thanks
 

JohnjH2o1

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I would think it would be easier to use three circulator relays. Then there would be no repiping necessary.
 

bentz69

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I would think it would be easier to use three circulator relays. Then there would be no repiping necessary.

I was adding zone valves because of the constant thermosiphon effect throughout the winter. I will get tremendous amounts of heat specifically on the 2nd floor when the thermostats are off
 

TCP

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Sounds like you have a bad flow check. I had the same problem on my old boiler. When the thermostat is off and not calling for heat you can tap lightly on it and see if it seats and if the pipes cool down eventually then it's the flow check that's gone bad.
 

Dana

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I was adding zone valves because of the constant thermosiphon effect throughout the winter. I will get tremendous amounts of heat specifically on the 2nd floor when the thermostats are off

Thermosiphon, or back flow? When the check valves are missing or leaking the return water from the active zone gets pumped back through the other zones even when "off".

Many circulators are shipped with an inexpensive check valve in the box, but they don't always get installed. Whether missing in action or worn out, replacements for those integrated check valves are pretty cheap.

If replacing it with zone valves it's important to size the pump so that the boiler still get's it's minimum required flow (if any) with just one zone calling for heat, and neither too much or too little flow on the different zones when all zones are calling for heat. You're going to have to do at least a little bit of math to neither over or under pump the boiler or zones. An ECM drive smart pump and some flow balancing valves can make it a bit easier to dial it in, but you at least need a starting point.
 

bentz69

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I forgot to mention from the start that my boiler is for heat AND hot water.

Sounds like you have a bad flow check. I had the same problem on my old boiler. When the thermostat is off and not calling for heat you can tap lightly on it and see if it seats and if the pipes cool down eventually then it's the flow check that's gone bad.

The only zone that has a flow check valve is the basement. 1st and 2nd floor does not have flow check valves for whatever reason.

Thermosiphon, or back flow? When the check valves are missing or leaking the return water from the active zone gets pumped back through the other zones even when "off".

Many circulators are shipped with an inexpensive check valve in the box, but they don't always get installed. Whether missing in action or worn out, replacements for those integrated check valves are pretty cheap.

If replacing it with zone valves it's important to size the pump so that the boiler still get's it's minimum required flow (if any) with just one zone calling for heat, and neither too much or too little flow on the different zones when all zones are calling for heat. You're going to have to do at least a little bit of math to neither over or under pump the boiler or zones. An ECM drive smart pump and some flow balancing valves can make it a bit easier to dial it in, but you at least need a starting point.

I have 2 taco pumps that honestly look like they are the original pumps from when this system was built in 1986. The 1 astro pump is much newer. I dont have much information because I moved in last year. But I do know the astro pump does not have the check valve installed because I found it sitting on top of the boiler when I moved in. When I called astro they recommended not using the check valve on hot water applications because of the possibility of the check valve deteriorating


 

Dana

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In 1986 the Taco pumps were black, not green- definitely not the original pumps.


When I called astro they recommended not using the check valve on hot water applications because of the possibility of the check valve deteriorating

There's some great product support for you! o_O

ALL multi-pump hot water systems need check valves to prevent backflow.

Since hot water is the primary application for these pumps it leads one to wonder what application the check valve was intended for. I'm sure the check valve doesn't deteriorate while still sitting in the box un-installed, but it's pretty worthless in that box-fill "application". Install it. Let it deteriorate- it might take 20 years, or it may out last the pump.

If/when replacing any of those pumps, install the check valve, and spend the extra $50-60 for an ECM drive version.
 

bentz69

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I wont sit here and pretend I know much about boilers since this is my first home (moved in last year) but I am trying to learn.

Im learning now that right above the 1st and 2nd floor pumps there are spring check valves installed. The basement has a flow check valve on a different part of the system. Im assuming they must be stuck open and Im also assuming that is the reason the check valve was not installed in the red astro pump










 

TCP

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I know you should not store your bike there.... its bad for the rubber tires, dries them out.
 
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