Cheapest valve that can shut off a 2” steam pipe?

Nsherman2006

Hi all,

I recently purchased a property in VT that has a living space and a storefront, both heated with steam heat from a single boiler. I would like to (for this winter only) shut off the steam heat to the storefront and only heat the house to get it through the winter for ski use without paying $5/gal to heat the unused storefront.

The boiler is a newly installed Peerless with two takeoffs from the header, one for the house and one for the store. I would like to install a valve on the takeoff for the store so that I can shut it off. This is intended to be a temporary fix, so the valve only needs to last a few months.

Could I use a brass ball valve for this application? I’d like to thread it into a short section right after the union and use it to shut off that section. Would it make more sense to just cap it?

Thanks!

mattmia2

globe? Should you use it? No.

I would say if this is temporary just cap it but I would need to know more about why it is temporary.

TonKa

The cheapest valves are the ones you probably already have - on the radiators.

Long Beach Ed

That should save fuel, but depending on the load, the boiler may short-cycle like crazy, not function properly and burn lots of fuel anyway. The boiler will be way oversized with part of the load removed. Shut the radiators, as TonKa suggests and see how it works. You can always get a valve down the line. You want a full-port domestic ball valve or gate valve. Chinese valves fail.

Check the price and you'll be capping the pipe instead.

bburd

Probably the easiest and least costly solution here is to rely on the radiator valves, and repair or replace those if needed; they are far less expensive than a 2 inch ball or gate valve.

Jamie Hall

Whatever you do in the way of valves -- there must be NO restriction in it. Full port Ball or gate. And if you do use a valve, you would be well advised to add a drip downstream of it, so it any steam does get by and condenses it has someplace to go, rather than sitting in the pipe and freezing... also, if the main you are closing is parallel flow, you will need a drip on the upstream (boiler) side as well.

Waher

Leaving a storefront unheated through the winter is a recipe for disaster. Your boiler is sized to heat the space and shutting off a branch of radiators isn't going to save you any money when it short cycles.

If you want to save money, insulate the pipes and turn down the thermostat. Rigid foam or even insulated foil rolls could be used to cover over the inside face of storefront windows to increase the thermal performance of the mothballed space.

pecmsg

I to agree shutting the steam supply to the store will creat more issues. 

Cover the radiators!

EBEBRATT-Ed

In addition, if you have separate returns from the store front the water in the returns will back up toward the store front when the steam valve is shut. Could freeze a return and possibly radiation

Nsherman2006

I wish I could just shut off the valves at the radiators, unfortunately while the house has typical radiators, the storefront has steam heated fans that do not appear to have a shutoff (I was only there for a few hours today to get the heat running, I won’t be back for another week or two)

I understand that the boiler will be oversized for the reduced load if I shut off one of the legs, but there are 7 radiators in the house and 2 steam fans in the store coming from a Peerless ECT-04. The house is around 2000 sq ft and the store is about 1200 and is certainly less well insulated. I plan to leave the heat at 50 when unoccupied and raise it to 65 when occupied, and I would like to find a thermostat with the ability to set a delta of 5 degrees so it kicks on at 45 and off at 55 to reduce short cycling. I’m thinking a cap seems to be the best way to deal with this, but I’m certainly open to convincing that it makes more sense to heat the unused space. I’m just having a hard time wrapping my head around that. Does anyone have numbers to illustrate efficiency loss from oversized boilers?

Thanks!

Danny Scully

Get some pictures of the emitters for the storefront the next time you’re there. Maybe TRVs would work for this situation.

bburd

Those “steam fans” in the store are probably unit heaters. If you leave the steam on and turn the fans off, they won’t condense much steam or put much heat into the space. That’s probably the best way to solve this.

I recommend against a wide thermostat differential “to prevent short cycling”. Since most steam boilers are oversized to some degree, the system is almost certain to short cycle on the pressuretrol during that long recovery. 

EBEBRATT-Ed

What @bburd said is probably be a good solution

FStephenMasek

Lack of heat may lead to condensation and extensive mold growth in that store space. Also, what would you do about water pipes in the store space?

pecmsg

FStephenMasek said:

Lack of heat may lead to condensation and extensive mold growth in that store space. Also, what would you do about water pipes in the store space?

Condensation

in the winter?

bburd

The unit heater fans in the store could be wired to a humidistat to control condensation.

pecmsg

How do you control humidity with just heat?

heating the air doesn’t dry it!

pedmec

Your not getting humidity in the winter. Everybody forget the nose bleeds from steam heat as kids. Mom putting a pan of water on top to add humidity to the air. If you were lucky enough you had the one that is design to hang from the radiator. just pour water in it.

Adding heat to the air reduces the relative humidity. Warmer air hold more moisture which in turn reduces the RH%. taking cold winter air and raising the temperature inside above the outdoor temperature will lower the RH.

Jamie Hall

pecmsg said:

How do you control humidity with just heat?

heating the air doesn’t dry it!

No, quite true. What does happen is humid air (people, cooking, etc.) leaks from the heated space into the unheated space, cools to its dewpoint, and condenses on everything in sight. Not too bad if it's on a window. Anywhere else and you are looking at mold and mildew you won't believer, never mind damage to any wood or plaster or what have you.

EdTheHeaterMan

Common sense says if the store is 70° inside and the outside air is 20° there will be a greater heat loss because the temperature difference is 50°. There will be more fuel used in this situation. By turning off the fan of a unit heater, the space will be a bit warmer than the outdoor temperature, but if it is 30 inside when the outside temperature is 20° then there will be a lower ∆T of only 10°. That will reduce fuel usage. The steam system will not be adversely affected and the fuel bill will be reduced. And the valve you need is already there. Here is a picture of what that valve might look like.

pecmsg

That had to be one very tight structure connecting to a large kitchen/ bath!

Jamie Hall

pecmsg said:

That had to be one very tight structure connecting to a large kitchen/ bath!

Hardly. I've had this problem in several colonial and early 1800s buildings where the owners were trying to save money by closing off parts of the house or structure. With more or less catastrophic results (like 600 plus square feet of destroyed plaster in one case... ouch...). Or a 5,000 or so volume library which had to be de-mildewed...

EdTheHeaterMan

pecmsg said:

That had to be one very tight structure connecting to a large kitchen/ bath!

Not necessarily, the amount of grains of water per pound of air is one of the factors in measuring relative humidity. As the air temperature increases, a pound of air takes up more space. So any given volume of air at 32°F (say 1 cubic foot) will take up a larger amount of space at 90°. Now without adding any grains of water to that pound of air, Any given cubic foot of air will have a lower relative humidity. That is because the same amount of water is spread across many more cubic feet. So any given cubic foot of 90° air will have a lower percentage of humidity. observe the psychrometric chart where 32° air at 80% RH (blue dot on chart) will have less that 10% RH at 90° (red dot on chart) when the same amount of grains of water are present, per pound of air
Now take that backwards and look at 50% RH air in the living room that might migrate to the unheated garage. The 70° 50% RH air when it finds its way to the open doorway to the garage (from the utility room in the heated house) that warmer 50% HR air will cool to say 40°. You can clearly see the green line from 50%RH/70°F as it gets colder those pounds of air take up less space and eventually the RH is at 100%. in order to get colder, that air MUST give up the humidity via condensation. And where does that condensation show up? On the coldest surfaces of the cold room.

How tight the house is and how large the kitchen is or how much humidity there is has nothing to do with the physics of the humidity. It is all scientifically measurable . Take hot air and make it cold you get condensation. Take cold air and make it hot you get dryer air.

I believe that @Nsherman2006 is just looking for the lowest cost way to save on fuel oil this winter. Just know that the colder space connected to warmer space, by walls or ceiling to floor can have some unwanted results. Keep an eye on the empty space to see if you need to add a little heat from time to time.