Vari-vents and cost control in single pipe steam heat system

McKern

Thank you for the suggestion.

I don't know what a heat timer is, but I'm sure that a quick search of this site will answer the question!

McKern

Vari-vents and cost control

Please help me understand how installing Vari-vents on radiators in over-heated rooms (as recommended by the condo board) will save on heating costs.

Here's the situation: 80+ year old condo building with 6 units/3 floors, plus garden unit. A thermostat in one of the first floor controls the boiler in the basement. How does installing Vari-vents on radiators in overheated rooms in other units result in energy saving? (My guess, given the location of the thermostat, is that this is related to the boiler cutting in and out in response to the pressuretrol, i.e., the burner won't be on for as long with Vari-vents. Is this close?)

Is this likely to be cost-effective?

(Less important technical question: I understand that traditional vents close when steam reaches the vent. What triggers a Vari-vent--or any type of vent that traps air in a radiator--to close?)

Thank you

Long Beach Ed

Specially Sized Radiator Vents

By properly sizing radiator vents, some radiators will be forced to heat faster than others. If the vents are properly sized, radiators in colder rooms will be permitted to heat faster than those in warmer rooms. Thus, when the boiler's heating cycle is completed, the cooler rooms will have radiators hot a larger percentage of the cycle time.

Properly sized vents permit air to exit the radiator at a specific rate. Vents with small holes slow the air, those with large holes speed up the air's retreat from the radiators.

Before a radiator can be filled with steam, the air in it must be exhausted through the vent. Thus, the radiator's air "holds back" the steam.

By using venting options to control the distribution of steam, a system can be operated on a lesser amount of steam than a system that heats unevenly. Overheating of some rooms will be eliminated.

The Vari-vent product is not a good choice for an apartment house. Tenants quickly learn to open the adustable vents all the way to maximize their venting, defeating the system. The vents have no floats to protect against leakage wich can result in plaster damage and claims.

The product is also inferior, with a very high failure rate. The manufacturer has ignored my complaints and claims in the past.

Look at a superior procuct with fixed venting rates, such as those vents made by Gorton. They come in different sizes for different vent rates and are not prone to tampering. They are made in the United States and last a long time. They are guaranteed.

The most common cause of bad steam distribution in one pipe steam systems is old, improper vents.

Long Beach Ed

Big Ed

Another Option

You should look into a heat timer as well a proper venting as Ed mentioned.

Unknown

Vari Vents

Based on what you stated about the location of the T stat, that is more likely to be your problem with over heating.

Before we get into air vent valves we need to check this situation. Boiler operating pressure!!

Your boiler should not be producing more than two pounds of steam pressure.

The pressure controller should maintain at least a 1/2 pound differential from the high and low pressures.

That means that the burner should shut down at 2 PSI and come back on line at 1 1/2 PSI.

At that pressure every vent valve that you choose to use in the future will work on the system.

Vent valves have what is known as a a drop back pressure.

Drop back pressure means that the steam pressure in the system must drop below a certain point or the vent valves will not reopen and allow air to re-enter the the system to prevent a vacuum from forming in the radiator. When a vacuum forms in the radiator you can get banging. If the vent valve does not reeopen steam cannot enter the radiator so a room or an apartment will get cold.

Because this a condomonium it would best suit the building to install a Heat Timer Central control panel or its equivalent.

These units are remotely installed and will measure the difference between the out side and inside temperature and supply heat in accordance to what the building needs on any day. The inside temperature can be adjusted at this panel. This means that all owners can agree on an indoor temperature that is both economical and comfortable for the building occupants.

Once the system is operating with this central control you can fiddle with vent valves for steam distibution. The Most important vent valves you need to deal with are the Vent Valves at the end of the steam mains.

Operating pressure and temperature control are the first things to take care of before working vent valves are removed and replaced with what some thinks is a better valve.


Jake

McKern

I appreciate the prompt reply. I can't begin to tell you how much bad advice we've received regarding the heating system.

Re Vari-vents--this isn't the first time that I've heard that there are better options. I'll pass this info on to the board. A major problem with our setup is that the radiators, valves, and vents are considered private property--owned by each condo owner. There is no consistent, system-wide strategy regarding vents.

I'm still not clear about where the savings factors into this, given that the thermostat in one unit controls the overall heat cycle. Does correct venting result in a longer period of time between the cut-out pressure and the cut-in pressure?

Thank you for your advice.