Removing a radiator

[mrcaptainbob]

I have a 4 zone hydronic system. I would like to remove one of the rads in one of the zones. How would I go about doing that without having water all over the place, and...after removing it, is the air that's introduced automatically purged in the expansion tank? Should I drain that zone first?

[LazyPup]

If you can valve off the zone on both the supply and return, you could then open the line at any convenient low point to drain that zone, possibly a union on the zone side of the return loop valve.

Once the repairs have been made you could loosely reattach the union, slowly open the supply valve and allow the supply water to fill the zone which would force the air out before tightening the union. Then open the return valve and the system should be back in operation.

[PlumBob]

Cap'nBob,

I have 4 zones, also. Fortunately, each zone is valved on both the inflow and outflow side, near the boiler. That allows me to shut down one zone, while leaving the others in service. Each zone also has a drain valve [u]inside that zone loop</u> so that once the zone is isolated it could be drained, while the rest of the system was still operating on line. Finally, each zone has a bleed valve somewhere at a high point in the loop (generally somewhere there is a copper L) that allows me to bleed air as the loop refills.

For my part, I never have enough valves. We once had to shut the oxygen off in an entire 400 bed hospital, while the plumbers installed additional valves, because we weren't able to isolate the wing we needed to work in.

LazyPup's suggestions are exactly what I'd do, except if at all possible, while I had the system down, I'd add valves if they're not already there.

PlumBob

[LazyPup]

Plumbbob,,I couldn't agree with you more on having extra valves. I have worked in schools, hospitals and large motels, where you dont dare shut the main water line or hydronic heat off everytime you have to service a line or fixture.

I am now in western Pennsylvania doing total rehabs on older houses that have sat vacant at least a year or so and no one bothered to drain the water and heating systems. As a result i usually have to begin by ripping out all the existing water and hydronic lines and replace them.

Given that these houses are intended to be rental properties there is a very strong likelihood that they will be vacant at one point or another during the coldest winter months. With that thought in mind, i make it a point to install zone valves when possible, as well as install addition system drain valves to facilitate easily draining the entire structure when vacant.

In the beginning the property managers thought i was crazy, but they are rapidly learning it is much cheaper to drain the systems than go to the expense and bother of repairing frozen water or hydronic lines as well as additional structurel damage from the water leaks. As i pointed out to them, the valves themselves are very cheap, usually in the order of $5 each, and what is another solder joint or two when your plumbing the whole house.

[mrcaptainbob]

I am fortunate in that there are shutoffs at both ends of each zone. Will look closer for any bleed valves. I think there are. They're near the solenoids and look like capped hose bibs. Would probably be a good place to let the air out at refill time, too. All that's left now will be to figure which zone belongs to which solenoid.
By the way, in another post I asked if it would be possible to separate each room of the house into it's own 'zone' and you replied that that's similar to the way school sytems are set up. Okay, so I build my neat little bypass and on the goes-outa end I leave it an open 'T'. At the goes-inta end I want to also have a 'T', but would like it solenoid controlled to shut off the bypass and open the rads for that room. What kind of valve is there for an application like that? Wheer would I go for them? I'd need probably eleven of them to separate the rooms to a point where I'd be comfortable with the final layout.

[LazyPup]

The attached drawing is typical of the electric solenoid control valves made by J.P. Gould Co.

You can get them with either 24vac low voltage coils or 120v line voltage coils. You can also get 120v line voltage t/stats from Honeywell so you could hook it up from the general lighting circuit in the room which would simplify installation.

They are made in sizes from 1/2" through 3" pipe thread

These type of valves are commonly used in commerial and institutional hydronic systems and You should be able to find the J.P Gould or a similar valve at any large HVAC supply house.

[mrcaptainbob]

Thanks, LayPup. I can't find Gould on the web, will keep looking. Tell me, would I need a 3-way valve? Normal position: open bypss/close rad? if a 'two-way', what's to keep the water from continuing down the bypass and not completly going through the rad? Kind of maybe a 50/50. Would I need to shut the pypass to force it all through the rad? I really like the idea of using the line voltage, but wouldn't I need to still connect the t'stat with the solenoid? May be easier to thread 24V wire....Thanks for your help.....

[LazyPup]

Normally when putting each room on a separate zone you dont run bypass. Run a main loop with drops to each radiator or zone and put the control valve on the drop. The control valves are then controlled by separate thermostates in the individual room or zone.

I would also put a manual gate valve on the return side of the radiators or zone so you could isolate one for service while keeping the entire loop up and running.

You then install a simple master on/off switch to control the boiler...on for winter..off for summer.

The boiler is controlled by an internal thermostat in the same manner as a hot water heater to maintain a costant temperature on the source.

The circulator is controlled by a strap on aquastat switch on the return line near the boiler and circulator location. The aquastat temp is selected to maintain a small differential temp on the loop. I.E. If the boiler is set to produce 180 deg supply water, you could use an 170 deg aquastat to limit the loop differential to 10 degs.

When a circulating loop system such as this is installed in large buildings such as a school or Motel they often use a separate loop for each wing, then individual rooms are run off the loop.

They then use UNIVENT heaters that have a finned coil and a blower arrangment. In that case each heater has an aquastat on the supply line that is connected in series with the room thermostat and the unit fan motor. When the thermostat calls for heat, the aquastat proves the loop is hot, then the fan motor is turned on.

In residential applications a variation of this can be acheived by installing a finned coil in a plenum in the same manner as an AC coil. The loop keeps the coil hot and the individual room or zone thermostat controls the forced air fan.


go on the yahoo homepage and input "solenoid water valves" in the search bar,,you will get dozens of sources.

[PlumBob]

Cap'nBob,

LazyPup has reminded me of one more thing I have in place - antifreeze. I had the plumber put in antifreeze when he installed the new boiler, and the entire system was drained. Fortunately, I haven't had to open any of the zones since it was installed, but I did have to replace the expansion tank, and lost a total of perhaps 3 gallons of fluid during that experience (by the way, I have a valve in place to isolate the expansion tank so I can change it easily) so the fluid hasn't been diluted much.

Note that this IS NOT auto antifreeze. I don't remember exactly what it is, but it's (supposedly) non-toxic (I still don't intend to drink it) as opposed to auto antifreeze which is toxic. The stuff is made especially for these systems. Propylene glycol-based, I think.

You might consider that, if your climate and other factors would warrant the expense. Of course, you have to pump it in, and for me that would require buying a pump - or calling the plumber.

PlumBob

[LazyPup]

Beleive it or not, there is such a thing as an edible antifreeze. I ran across it a few years ago at a camper supply house. It is made to put into the water holding tanks on boats and campers for long term winter storage. I dont think i would want to drink it, but it does work very well for winterizing those systems, then i would drain and flush in the springtime.

As far as pumping the chemistry into you hydronic system, there is another much older method that is commonly used on steam boilers. Large steam boilers require a daily blowdown to relieve sediements and minerals which are brought in through the make up water. As the system is blown down a substantial amount of the anti-fouling chemicals are lost. To compensate the engineer takes a sample of the water and analyzes it to determine the actual level of the chemicals in the water, then he adds additional chemicals in liquid form to make up the loss.

They use a simple plumbing arrangement that actually uses the internal pressure of the sytem to insert the chemicals.

When i worked in the school system I had 22 boilers to check twice a week.

See drawing below......

[PlumBob]

LazyPup....

Totally Cool.....

I actually have a 5th zone - it's just a stubbed out loop - maybe a total of 6 feet long, right in the inflow and outflow headers of the other zones. I could put the antifreeze adder in there. Hummmmm..

I'll bet the stuff tastes like - chicken? Probably more like - goose liver ;-(

PlumBob

[LazyPup]

On a steam system the chemical injector in mounted above the natural water line of the boiler, so the vessel normally only contains steam, which vents off when the upper valve is opened.

If one were to install an injector on a hydronic system the injector vessel will be full of water at all times. You would need to make a minor modification by installing a tee on the bottom with another valve to drain the vessel.

To add chemistry you would close both the valves from the loop to the injector, then open the bottom valve to drain the vessel and then open the top valve to vent the vessel so it will drain completely.

When its drained you close the bottom valve, pour the chemisty in through the top valve and close the valve. Then open the valves to the loop.

If you were to install the injector on your extra short loop you would want to insure that once the injector has had a couple minutes to pass the chemistry into your system you must then close the zone valves or you would have a short cycle loop through the injector.

In reality, it is so seldom that one needs to add chemicals into a residential heating system, i dont think it would justify the expense and bother of installing the injector.

[mrcaptainbob]

You guys are good. When I start the remodeling project for my wife's bathroom, I'll add a loop to the furnace.