Upgrade with zone board for future zone addition

garfungle

Hi,

My current boiler is not setup with a zone board. I'm looking to add a zone for some toe kick heaters in the future, but I want to be able to turn my boiler on before it gets to cold out and isolate the toe kick heater zone from the rest of the house. I currently have two branch circuits (non zone), that I would like to leave as my primary heating. The toe kick heaters are really just for keeping an addition off the back of the house warm. This would create two zones — one for all radiators / baseboards in the house and a second for the toe kick heaters. I would like to not have to drain the system once I've added the toe kicks. I've attached a simple drawing of the current boiler configuration. I'm looking for suggestions on how to modify the system to easily allow for this addition. I'm also not sure if the current position of some elements of my boiler are even correct (see expansion tank location). Let me know if you need more detail.

Ironman

You’re gonna need more than just a zone panel. You would also have use zone valves or at least two circulators.

If you use two circs, the new zone would have to Tee in below the existing circ and both would need flow checks.

That’s a fairly large supply line coming out of the boiler, so a zone valve that size would be expensive if you choose that route.

It may be easier if you piped the boiler p/s and then Teed off of that to the zones. That would also give the boiler protection from cold shocking.

garfungle

@Ironman I had been leaning toward the two circulators. If I pipe it as a p/s, wouldn't I need three circulators? One for the primary loop and then two for the two zones? The two branch circuites provide their own 3 inch supply and return, which are teed near the inlet and outlet of the boiler as shown from my diagram. These 3 inch pipes have long runs throughout the basement under the joist bays. Can I step up and down the pipe diameter on both the supply and the return or will that affect flow/pressure too much? In the suggestions above, you said that a zone valve of that size would be expensive. Could I not just start from a lower diameter supply pipe through a zone valve and then expand the pipe diameter after the zone valve (not saying this is good — just curious)? Additionally, how can I isolate each zone with the intent that I will introduce a new zone at a later point, but I don't want to drain the entire system. Ideally, I would open some valves.

HVACNUT

IMO, if you're going to drain down and cut it open, you might as well do the whole thing right. It's a job either way, so it's not much more to pipe it correctly. With the appropriate isolation valves.

Big Ed_4

Looking at the iron supply , What type radiation is up stairs ? You may need to supply a different temperature per loop. …..

garfungle

@HVACNUT I already have it drained down. My current worry is that I'll need to start it back up before I finish a renovation I'm currently working on. I'd like to still have my primary zone working and heating through all the rads while I finish up my renovation and install the toe kicks in the winter. Since I currently have it drained down, I figured I could isolate the new zone with air, but I wasn't quite sure how to accomplish this with the piping or if I needed additional isolation valves so that I don't introduce air into the primary heating zone.

@Big Ed_4 The whole house is currently a single loop with two branches (maybe you would consider this two loops). There are basically multiple tees but no zone board or isolation valves. I don't mind having a single zone for controlling all of my rads. I plan to add some toe kick heaters, which need to have a separate zone, so I can control their output isolated from the rads. This would require some sort of way of independently controlling each zone, so I figured I would need a zone board.

EdTheHeaterMan

Are you looking to do as little work as possible?

OR

Are you interested in doing it right?

Your system is piped wrong, however, it will work just fine in this wrong configuration. That is because there lots of wiggle room in this design and you can always go and make needed adjustments over the season.

At some point, in the past, your system was equipped with a standard compression tank for the heated water to expand. It may have been in the attic or it may have been in between the basement ceiling joist. In any case, that needed to be drained from time to time when it became waterlogged. When the replacement boiler was installed years ago, the installer used an Extrol® expansion tank to eliminate the need for draining the compression type expansion tank. First problem solved by changing tank types. But the circulator location and other air controlling designs were not implemented back then.

Now you want to add a modern design (compared to the gravity design of your existing system) radiator to your older design heating system. You may do it at a lower cost but if you encounter some future air problems as a result of your existing design, you may be unhappy that you decided to go cheep today. You may get lucky, and everything works out. But you may not.

If you are interested in eliminating air problems, you can make some design changes while the system is empty, before you fill it back up. and you don't need to worry about the zone control panel right now, that comes when you are ready to wire up the new radiators

I can help you with some ideas and others herein can add to it. I like to go old school because those parts are less expensive than ECM pumps and other hi tech designs. keeping it simple will make for a better low cost, low maintenance system.

One thing you want to address is the fact that your current design may be causing flue gas condensation which will make the boiler fail before its time (30 years in stead of 50 years) for example. and after 30 years of rust and corrosion happen, you will just thing that is how long it should last even though that same boiler properly installed may last 20 more years. You will never know!

garfungle

@EdTheHeaterMan I've been reading more about some of the designs and best practices and I came to the same conclusion about the expansion tank. I plan on redesigning it with a pump away strategy. I plan on piping the fill valve to the compression tank and then after the expansion tank I would put my circulators to the zones. Is this what you meant by the right way? From what I can tell in the current design, the expansion tank is not located at the point of no pressure change since the circulator is pumping into the boiler. The one thing I'm nervous about is breaking some of the tees on the old cast iron pipe. There are two branches in the current single zone setup. There is no logical separation between the branches (they mix and match rads on different floors and rooms). I'm not sure if I should run the risk of breaking some of the couplers to repipe the two branches into separate zones or just let sleeping dogs lie. Any input would be helpful.

EdTheHeaterMan

To be clear, the expansion tank IS the point of no pressure change! Where you place the point of no pressure change is why some systems get air locked and others don't.

To understand the point of no pressure change you must realize that unless you add or subtract something from a closed system, the pressure at the expansion tank can not change. If you put the circulator next to the expansion tank, and push the water in a closed system towards the expansion tank, the water will not enter the tank because there is no place for it to go. and if you were able to force more water into that tank… where would you get it from? The higher pressure of the pump? If that water actually went into the tank, would that missing water from the system leave a hole in the system somewhere where that water used to be?

likewise, if the pump was pulling the water away from the tank, and actually emptied the tank into the closed system, where would that water go? if the system was already filled with water, there would be no place for it to go, inless you have a pipe or something that expands like it was on a cartoon.

The only way that you can put water in the tank or remove water from the tank is to open the closed system and put more water in, or take water out so the compressed air will absorb the additional water and compress to a higher pressure or expand to let water out and expand to allow the water to leave the tank. Any given circulator pump can not move water in or out of the expansion tank on a closed system.

See illustration to follow in about 5 minutes. https://heatinghelp.com/systems-help-center/the-point-of-no-pressure-change/

This shows how the pump pressure differential is added to the system static pressure

The next one shown how the pump pressure differential is subtracted from the system static pressure

This illustrates a system that will have air problems.