Is zoning worth it?

jac34

I am switching over my oil fired hot water boiler to propane come spring. Current set up is 2 zones; one thermostat is serving 24 cast iron rads on three floors. the other zone is the boiler running pipes to an air handler and pushing out forced air in kitchen/breakfast room.

The rads break out to 9 on first floor, 11 on second, 4 on third. I'm considering putting the first floor on its own zone and the 2nd/3rd floor on its own zone with a thermostat on 2nd flr.

I've had some contractors look at it and it is possible. They would need to run a new pipe off the boiler and tap into the 9 rads. They suggested just doing the supply side and leaving the return pipes on the same return. all the pipes are accessible in open basement ceiling but I'm sure it's still a fair amount of labor to untie these and pipe the new main.

It will all be determined by the estimate $$, but is it wise to do this for the long haul? Meaning, can you expect a fair amount of fuel savings by separating the floors into zones?

The other annoyance is we have a wood burning fireplace in the room where the thermostat is located. The living room heats up quite a bit and then the rest of the house gets cold.

Big Ed_4

For comfort , every floor and wings should be zoned . Not sure if possible , but did you look into TRV's .. Then you can set every radiator ... I would also recomend and outdoor reset , variable speed circulator and an mixing valve to temper down the supply water for the cast iron over the air handler ...

Zoning by just separating the supplies and not separating the returns will not work ... You will get ghost flows and over heating

Gordy

When you’re not burning the fireplace how is the balance of heating to all floors, and rooms?

If given the option of zoning how would you utilize it?
Is there certain rooms not used, or certain levels not used that would be set back?
Is comfort the goal, or fuel savings?

I assume the portion with radiators is an old converted gravity system?

The installation of trvs properly piped would offer precise control at each radiator. Then you could set back areas, or rooms verses floors. For me properly piped would be home run each radiator to manifolds. This allows each radiator to get its required flow, and the trv modulates that based on temp.

Bottom line is what you seek from zoning, dollars you want to spend to get a rock solid system.

How much you save by zoning will depend on how it’s utilized, and the time for payback in savings vs installed upgrade.

Then there is the unintended consequences of zoning.

Is the boiler sized properly for the heat loss?

Will a new boiler be installed? If so what type? Zoning can, and will lead to short cycling if not properly thought out. Outdoor reset should be part of that plan.


As far as the wood burning appliance shutting down tstat when used. Maybe a better tstat location could remedy this problem.

bink

I did what you are proposing using three zones using a common return. Works good especially with my new system with pumping away from expansion tank actually have 4 zones 3 for baseboards for each of three levels and one for indirect water heater.
Pros: nice to have individual control saves fuel by allowing lower temperature in 1 st and third keeping living area warmer.
Cons: one zone is now small length of baseboard creates a short run time
Also Extra zones valves or circulators more potential maintenance. Since I had the new system installed three years ago have had two zone heads fail and had to be replaced. The 4 zone valves are on a manifold to the right on photo did not realize they were not in photo
Good luck
.

unclejohn

Zoning is more comfort than savings although you will most likely see some savings as well.

jac34

I’m mostly concerned with comfort as out master bdrm is always about 5 degrees colder than other rooms on same floor. Wondering if this is flow issue and would TRVs even solve this? Would love to save some fuel as well!

We do have a 3rd flr with 2 spare bedrooms and a bath that we rarely use. When we put the new boiler in we need to either zoning or just beef up the circs to get better flow.

I’m not sure if this was once a Gravity system.

Thanks all. A few questions:
How do TRVs work? Are they expensive?
Can you explain ghost flow?

Big Ed_4

A thermostatic radiator valve (TRV) is a self-regulating valve fitted to hot water heating system radiator, to control the temperature of a room by changing the flow of hot water to the radiator...

We call it an Ghost Flow because the first time an machanic comes across this problem they will be scratching their head in the basement looking at the pipes , figuring how this is happening ...It happens by an mistake and misplaced pipe tees.. Ask me how I know that .. What happens is when one zone calls for heat its returning warm water migrates up into the other zone ..

Hot water wants to rise and cold water wants to fall . The old gravity system used that principle to move heated water up to the radiator .Just give it an open loop of teed pipe. Each one of your radiators is an open loop . Sure both supplies are flow controlled . Rule of thumb to stay out of trouble .. Return each teed zone to it's common return before returning back to boiler .. Physics finds an way.

Gordy

If your system has large diameter supply, and return pipes it probably was a gravity. Got some pics at the boiler room area?

jac34

can someone explain fire tube vs water tube?

flat_twin

Water tube. Higher resistance to flow and requires primary /secondary piping.
https://www.youtube.com/watch?v=btpGf5kVvKI

Fire tube. Lower resistance to flow. Can be piped primary /secondary or may be piped direct if flow requirements of the heat exchanger and distribution piping are the same.

https://www.youtube.com/watch?v=tVfBNezvf9M

NY_Rob

Both designs require routine maintenance BTW.

jac34

Is one better than the other for marrying to a cast iron radiator system with large mains?

NY_Rob

Both designs will work well with cast iron radiators.

Many here consider the "Fire Tube" design lower maintenance as it produces a semi self-cleaning effect due to the wash down action of the condensate as runs down and through the HX on it's way to the condensate trap.

jac34

I have received 2 different opinions on how to zone. One design is to go from one rad to the next creating a loop. The other is the way the current rads are set up-each has its own supply and return coming back to the main.

What are pros and cons of both and is it advised to keep it consistent with rest of the house? There is a difference in the labor so I'm not sure what I'm missing.

hot_rod

It depends a lot on the individulal system, there is not a one answer.

When you put heat emitters in series, you get a temperature drop at each emitter. Depending on the size of the radiator and load in that area it could be considerable. So either additional downstream radiators get upsized to work at lower temperatures or limit the series to 3 or 4. It's hard to know on your system without some calculations like room by room load, and measuring the radiators in each area.

The home run system offers more flexibility for zoning and adjusting. Each radiator could be zoned by actuators on a manifold with individual wall t-stats, or TRV at the emitter.
In some cases a couple rads could be on one home run, but the load calculatiozwould be the only way to know for sure.

Often 1/2 pex is adequate for home runs, so it's easy to retro fit that type of system. Less piping loss with pex compared to large diameter iron piped systems.

jac34

9 rads would be on this series; it's referred to as a daisy chain? I thought that was more for baseboard systems but I'm a novice so have no clue.

don't want to go the cheaper route and then it doesn't work.

hot_rod

Are you starting from scratch, or keeping that existing large diameter main piping?

Has it worked well in the past and you just want a boiler up grade and a few zoned?

Sounds like you have had issues with the 3 rd floor performing.
To accomplish all your wish list it may be wise to do the home run system and have unlimited zoning and adjustability.

jac34

Just upgrading boiler as I am switching to propane.

During the switch, I’m looking to separate 9 1st flr Rads on their own zone and keep 2nd floor (11 rads) and 3rd flr (4) on one zone.

The only issue I really have had is the master bedroom is not as warm as some other adjacent rooms. Not that this will fix it, but I will have them take a look.

What is home run system?

hot_rod

Every heat emitter gets a supply and return line, all joined to a manifold back at the boiler. Any mix and match of rads will work as each one is adjustable and zone-able.