Zone #1 covers two stories, should I split it into 2 zones?

Oil boiler, baseboard, 2 story colonial ~1800 sq. ft.

Zone #1 covers two stories. Since the thermostat is on the first level and since heat rises (duh!), the zone is constantly active and the upstairs becomes like an oven.

Would splitting this zone, into two zones, solve my problem?
Would this new configuration operate more efficiently?
Who do I call to get this work done? Plumber? HVAC guy?

 

Hi K,

Me being the nit-picker that I am, I want to clarify this a little bit because 'as stated', it is not exactly true.

More correct:

Heated AIR 'rises'. It actually doesn't 'rise' all by itself though, it really 'floats' on cooler air.

Heated WATER does the same thing.

Being that either water or air when heated are less dense than their cooler counterparts, that air or water will 'float', like a hot air balloon...

HEAT RADIATES TOWARD ANY DIRECTION THAT IS COOLER.

OK, that's off my chest now...

A house acts as a 'chimney' of sorts when talking about air flow.

When you heat the air in the home it wants to float up and out every exit it can find upstairs. When air exits upstairs, cooler air is drawn in downstairs... the 'chimney' effect.

Air in- and ex-filtration is the single biggest heat loss in any home. MORE than lack of insulation.

OK, so that's one of the reasons that the downstairs is cooler.

The heated water in your system pipes does the SAME THING as the air. It sets up 'gravity flow' in the pipes and even without the pumps running, the water can still circulate. The hotter water flows to the top and the cooler water flows to the bottom. This happens BETWEEN heating cycles.

This is another reason that your upstairs may be much hotter than down.

We'll get to the zoning, I promise, but you need to understand these things in order to get to a root cause.

I would like to try to determine if your system has a functional FLOW CHECK valve installed. This valve will prevent the 'gravity flow' problem.

Wouldn't it be nice if the solution to your problem was as simple as turning a valve handle to the correct position?

Can you take some pictures of all the piping and valves around your boiler and post them here? Try to get them as well lighted and in focus as possible. I want to see if you have a flow check valve on your piping somewhere.

 

I can take pictures on Tuesday, if needed. However, I'm next to positive that I DO NOT have a flow check valve. Other than the normal water feed valves found throughout the system, the pressure reducing valve (from the city water supply line) is the only thing with a lever on it. IIRC, the supply line coming out of the boiler attaches to the expansion tank and then splits to two separate lines which lead to individual zone valves. From there the pipes go to their respective zones without interruption.

 

Some types of flow checks don't have a lever, but you would still see the 'device' in the pipelines somewhere.

You could also have a flow check installed in your circulator pump, but in some cases this may not be enough to stop gravity flow depending on the details of exactly how the system is piped.

Take a look at the pump and tell us the make / model. If it has the internal flow check you might see the letters " IFC " in the model number, or there may be a label or sticker on the pump indicating this.

Adding zone valves almost always stops gravity flow, so you could end up finding that to be the best solution in the end.

I just want to make sure you don't do un-necessary work and we look for the 'simple fix' first.

Have you lived in the home for time enough to know if this is an on-going problem that you've put up with for years? Or is it a new to you home? History, if you know it, sometimes helps paint a bigger picture.

 

I'll take a look at the water pump tonight and report back.

Only been here a few years but I'd say it's a pretty consistent issue, nothing dramatically changed.

It just seems counter-intuitive to have the system kicking while it's 75-80 degrees upstairs and I'm already seconds away opening up the window to blast in some cold air.

We're also teetering on the idea of getting a fireplace insert to help with the oil bill. I'm hoping a resolution to this heat discrepancy issue could save on our oil bill so that we can stop considering the fireplace insert.

 

Yeah, that's not a good thing at all. Let me ask this, what is the thermostat set downstairs? For you to have that huge a difference between up and down it seems as though there's more to it than heated air rising.

Are your baseboards of the type that have a copper tube with aluminum fins? or are they the cast iron type? Hopefully they are the same type throughout the home?

When was the last time the covers were removed and the dust and pet hair vacuumed out from the fins? Perhaps the downstairs baseboards are blocked? You would be amazed at what even a light coating of dust can do to severely reduce the heat output of fin-tube baseboard!

How about wall to wall carpeting? Is the downstairs all carpeted? Does the carpet go UNDER the baseboards and obstruct airflow into the bottom opening? If so, you need to get that opening cleared so that air can freely flow through the baseboard unit.

Waiting for a few pics...

 

Picture of the circulator attached.

Downstairs thermostat is set to 60-65. Anything higher and you have to rotate me every 5 minutes while I'm upstairs.

Baseboards are all copper tube with aluminum fins. All went through a massive cleaning a few years ago (take off covers, vacuum, hit all the fins with a spray bottle, etc).

Entire house is hardwood flooring.

 

Wow... to see that kind of temperature difference between floors means that the problem is more than heated air rising.

I'm quite sure that you've got some gravity flow going on there.

I thought you were going to post some pics of the system piping around the boiler?

 

Sorry for the delay...attached are some pictures of my setup.

The control value nearest goes to one room on the downstairs level.
The control value furthest goes to the rest of the house, both upstairs and downstairs. This line splits via a T-fitting downstream to separate the downstairs/upstairs lines. They combine via a T-fitting in the basement upon return.

 

I don't think I had previously realized that you already have zone valves. These should for the most part eliminate gravity flow issues.

Also, it appears that there is a domestic hot water coil in your boiler and that the boiler is a 'warm-start' model and keeps itself warm 24/7.

I will study the setup at greater length this evening...

 

With the zone valves above the boiler like that, I can't envision how you would be getting any gravity flow in the system.

You are certain that the existing zone valve is actually CLOSING, yes?

It just seems like you are describing to big a temperature difference between the up and down floors to be a case of heated air rising.

Is the upstairs of newer construction perhaps, and more tightly air sealed and insulated?

It may be possible that when the home was built, they simply installed baseboard all around the perimeter and that there is actually TOO MUCH baseboard in the upstairs rooms. MANY homes are built this way without thought to the actual amount of baseboard that should be installed in each room.

Each room has a certain heat loss and in order to have a 'balanced' heating system, the baseboard (which typically emits about 550 BTUH per lineal foot of element) needs to match that heat loss and be proportionally the same throughout the house.

If you wish to explore this idea, you could download the Slant-Fin program at the top of the forum list and run the numbers yourself.

Moving back to the original question...

If you decided to run separate zones (which in the end might be the best solution) you would need to 'lose' that zone valve above the boiler that controls the 'rest of the house' and install one on each floor pipe after they exit the 'tee' split.

They do make wireless thermostats that would eliminate having to pull a thermostat wire if that is difficult.

Another option would be to leave the existing zone valve in place, and add a single zone valve to the upstairs split. Wire it to a thermostat... but NOT to the boiler. Since the upstairs is ALWAYS warmer than the downstairs, when the upstairs needed heat, it's zone valve could just open and wait for the downstairs to come on and kick the boiler.

Lastly... if you DO decide to run the heat loss program and find that the upstairs does in fact have much more baseboard than required, you could pop the covers and use heavy duty aluminum foil to 'foil over' that portion of the baseboard that is in excess.

In fact, this might be worth a try even if you don't run the heat loss. Aluminum foil is a lot cheaper than re-working the zoning, or a fireplace insert. Maybe start by covering half of the upstairs elements in each hot room and see how that goes.

 

Another question...

When the main zone is calling for heat, if you put your hand on the pipes returning to the boiler before they join at the tee, are they both relatively the same temperature?

Do the downstairs baseboards get just as hot as the upstairs?

It is always possible that the loop has a persistent air blockage and it's impeding the flow in the downstairs loop.

 

Ironic you ask this, it's actually the upstairs pipes that have the most air in them. On more than one occasion the upstairs had no heat because of air in the lines. Every time I bleed the downstairs lines, I get little to no air.

Same construction, but I tend to believe the downstairs is less air tight. There are a couple of small spots where cold air is pouring through that I will shore up this fall. I don't think these are game-changers, but should help. We also have an open fireplace with no covering (we never have fires), flu always closed...I'd imagine this is a pretty decent loss of heat too.

Yes, the wire install is extremely time consuming, however I already completed it while running other low voltages wires, so that's at least one thing off my plate.

I will look into the calculations, however I'm almost certain that downstairs might have too little baseboards. The previous owners renovated the kitchen and I can clearly see holes where baseboards were removed from the kitchen area.

One other question...would splitting the zone actually help in lowering our oil consumption? Convenience is one thing but I'm more interested in saving money. Obviously, the ROI is of most interest; but I'll worry about that when I start getting estimates.

Thanks for your help with everything!

 

That would be sorta typical, being the highest point and all... but sometimes, depending on how the pipes are run, it's possible to have partial blockages in lower zones as well.

That's why I asked whether the return pipes are both equally hot. If the downstairs return is noticeably cooler I would start looking at WHY? ...

How are you bleeding them? Do you have the manual air bleeds placed around?

If the air bubbles aren't under the bleeders and stuck in a high spot in the piping elsewhere, you won't get the air out. The flow of those little bleeders isn't enough to move air bubbles.

But, it might not be a problem anyway... just food for thought.

I'm sure it is. The fact that a 'draft' will exist in the chimney will actually 'suck' the air out of the house in spite of the flue damper being closed. They really don't seal all that well.

Put your hand in front of the electrical outlets on the outside walls on a cold day... you would be surprised how much leakage you get through those. Install those foam gaskets (cheap) made for the job.

Air leakage in a typical home usually amounts to a total quantity that equals a window wide open. It's the small, seemingly insignificant, things that incrementally add up.

If you don't feel cold drafts UPstairs, it's usually because the heated air is going OUT those same areas. A home is like a chimney, when the air inside is heated, it DOES want to rise because of pressure differentials. You feel the drafts downstairs because that is where every leak is sucking cold air IN. Every ounce of cold air that comes IN must be countered by an ounce of heated air leaking OUT. So don't neglect sealing the upstairs as well. Often overlooked are things like ceiling light fixtures and the like. If you can slow the warm air leaking out, you will slow the cold air being sucked in.

What is wrong with people?

I watched one of the home shows on TV one time where they were renovating the kitchen. There was a small mud room at the rear entrance, and a door between it and the kitchen. The mud room had a decent sized radiator in it. There was another radiator on the wall next to the door between the mud room and the kitchen. They wanted to open the wall and remove the door.

What did they do? Removed BOTH radiators and replaced them with.......... NOTHING! Talk about dumbazzes.

That's kinda tough to pin down, but I would say that it's likely. Might not be a whole bunch, and maybe not enough to notice unless you look at an entire heating season and compare it to actual 'heating degree days' (just looking at oil usage alone is meaningless... it needs to be referenced to demand. One winter may be colder or warmer than the preceding one.)

Let's look at it this way... if there is a deficiency of heat emitters downstairs, then the boiler has to run and run to try and keep up with the heat loss. The thermostat will keep calling for heat and take longer to satisfy. The extra heat that is being dumped upstairs is for all intents wasted.

If you really feel that the downstairs is now UNDER radiated, you might investigate ways to make up the deficiency. Maybe add a 'kick space' heater in the kitchen to make up for the removed baseboards there.

To get a real 'feel' for this, you would have to run the numbers. Even a quick and dirty whack at it without being 100% accurate might show that there's a big imbalance between UP and DOWN stairs.

If there IS a deficiency downstairs, splitting the zones would help to keep the upstairs cooler and not waste that heat going there, but the system will still struggle to heat the downstairs.

I would gather as much data as possible and then decide what the root cause is and determine where your money is best spent.