Replacing old radiator valves and their flow

Dan McCartney

I am replacing all the old vlaves on my 1920's era radiators as the seats are rusted away inside and they are open full bore all the time. I would like to know how I should regulate them once I have all these new valves for optimum performance and efficiency? 1. May I open and shut them as I please depending on room occupancy, or should they all remain open slightly, all the time, for consistency? 2. On one of the radiators that I restored, it seems to fill on the valve end, and on other, it seems to fill on the non-valve end? It would appear to me that if the hot water fills on the valve end, then you are restricting the entry, and if they fill on the non-valve end, then you are restricting the exit of the water? Why two different ways and how should I manage each? 3. Where can I read more about managing the valves throughout my home? 4. I am having the radiators sandblasted and am applying a clear Kyrlon lacquer. This looks great; any problems in doing this? Thank you so much! Dan McCartney, Toledo, Ohio.

Dan McCartney

New valves on old radiators

I am replacing all the old vlaves on my 1920's era hot water radiators as the seats are rusted away inside and they are open full bore all the time. I would like to know how I should regulate them once I have all these new valves for optimum performance and efficiency? 1. May I open and shut them as I please depending on room occupancy, or should they all remain open slightly, all the time, for consistency? 2. On one of the radiators that I restored, it seems to fill on the valve end, and on other, it seems to fill on the non-valve end? It would appear to me that if the hot water fills on the valve end, then you are restricting the entry, and if they fill on the non-valve end, then you are restricting the exit of the water? Why two different ways and how should I manage each? 3. Where can I read more about managing the valves throughout my home? 4. I am having the radiators sandblasted and am applying a clear Kyrlon lacquer. This looks great; any problems in doing this? Thank you so much! Dan McCartney, Toledo, Ohio.

Mike T., Swampeast MO

The valves I've seen from that era don't have seats. [Of course yours may be different.] Generally the stem attaches to a big rotating cylinder with two holes--one the full size of the tapping and other (180° opposite) very small. The little hole ensure some flow even with the valve turned "off". Generally the valves can be repaired with little effort. Those old valves were more about providing very little restriction to flow than positive shut-off. While convention usually finds them on the supply side, it does not matter with plain valves. Particularly if your system originally operated under gravity and has been converted to forced circulation, balancing the hand valves is a royal PITA--it's hard to find the middle ground between very little flow and a lot of flow and, unfortunately, the settings are interdependent--e.g. changing one or two will frequently change flow in the rest.

Lacquer over bare iron shouldn't be any problem.

Since you're removing them for sandblasting, now would be a GREAT time to investigate thermostatic radiator valves (TRVs). These valves allow each radiator to become its own "zone" independently of all the rest. They replace old valves directly and no wiring is necessary. Little (if any) other modifications are required in the system. Cost will be somewhat higher than plain valves, but since the old valves are a definite specialty item in most areas, you'll probably find that the TRVs and actuators won't cost a whole lot more.

Rich Kontny_2

Thanks for your reply, Mike; may I press you a little further? When I examined the insides of my old valves, there was nothing left there; even the stem was rotted away, so I never saw a seat or this cylinder that you speak of. Maybe opening others will show me more. I can picture what you are describing, though. Since my system was originally a gravity system, then it would seem that closing off a radiator valve should not upset the flow to the others, if anything, strengthen it, since it is not a loop ? Could you comment on this?

I do notice, on the two radiators that I have recently replaced the valves, that opening them just a hair still gets them pretty hot. For example, it takes about 8 revolutions to fully open it (or at least, that's how many times it can be turned). One revolution gets it to about the same temperature as the eight, eventually. Any comment?

Regarding natural gas consumption, if I shut off a radiator, in theory, does that mean I am saving gas? Also, if I shut off radiators in a room, for, say, a day, then it gets cold in there with the door closed. When I turn the radiators on again, whill it take even more fuel to get the room up to temperature again? Have I gained nothing? I am desperate to learn how to use these puppies!

These thermostatic valves that you speak of sound like a good thing. I rented an apartment that had them once, however, and they never worked right. Also, I have a historic home, and really want to keep the "old" look. Perhaps they have come a long way in 15 years, so I will re-investigate.

Lastly, (and thanks for your patience, but you're the only person I have talked to about this) could you help me understand the valve at the supply and the exit side. If the valve is at the supply side, and is shut off, then I see the pipes up to the valve, staying hot, but not the radiator. If the valve is on the exit side, then the hot water would still be allowed in the radiator, and it would stay hot? Is my thinking wrong? Again, I am most grateful for your counsel! Dan

Plumbob

Plumbob

> If the valve is at the supply side, and is

> shut off, then I see the pipes up to the valve,

> staying hot, but not the radiator. If the valve

> is on the exit side, then the hot water would

> still be allowed in the radiator, and it would

> stay hot? Is my thinking wrong? Again, I am

> most grateful for your counsel! Dan




Water cannot flow in unless water flows out; this is Einstein's famous Law of Conservation of Water. If water cannot flow, it cannot carry heat (*). It does not matter where the valve is, as long as there is a valve somewhere; if water flow is stopped, heat supply is stopped.

Re your other questions, controlling the heat in one room won't save any money you'll notice, and it won't cost any money. It is just for comfort. As you've noticed, you can't control the heat very well with a manual radiator valve, but but TRVs work very well with hot water heating in all situations where there is too much heat. (They cannot increase the flow, only reduce it.) I don't know what the problem was in your old apartment; are you sure it had TRVs? Was it hot water or steam?

(*)This statement ignores conduction, and convection within a single pipe closed at one end, which are both small effects in this situation.

Mike T., Swampeast MO

You may have valves with which I am unfamiliar. The ones I mention use a single revolution to go from full on to off. Since flow is so much higher when a gravity system is converted with a circulator it gets extremely difficult to regulate the flow--even a small opening will provide quite a bit of flow and heat.

TRVs haven't really changed in decades--the design principles and reliabilty are that solid. In apartment buildings around here TRVs are often added only to a few radiators--those that tended to overheat greatly. The TRV then becomes a "high limit". Also, if they don't have a constant supply of heat and circulation, they really can't do their job--if the boiler fire was controlled elsewhere in your apartment, the TRVs may well have been "starved" much of the time.

When they are installed on ALL radiators with constant water circulation and the boiler controlled by outdoor reset, you'll find that they work marvelously and with extreme reliability.

As long as yours is a two-pipe system (the majority of gravity systems were), you can shut down any radiator(s) without affecting the rest--flow may increase a bit, but that's all.

Setback is a rather contentious subject. My belief is that if you completely shut down a radiator in the morning and then turn it back on at night, that you have saved very little energy at the expense of reduced comfort. All of the objects (walls, furniture, etc.) have cooled and must be raised in temperature to achieve the same level of comfort. My setback philosophy is to find the coolest temperature at which you are generally comfortable and use only modest amounts of daily setback--and set-up when/if you are uncomfortable at your "normal" temp. For unoccupied space, you can set back as deeply as practical.

As Chuckles said, it doesn't matter at all on which side a plain valve is installed. Flow through the branches to that radiator can ONLY be what is allowed by the valve--regardless of it's position. TRVs however are directional--the right angle versions are installed on the supply side only.

Rudy

Thanks to all of you who have responded to my inquiry about radiator valves; you have offered me great thoughts. My interest in my heating system continues to grow and I am anxious to learn more about it! I find the historical aspect of hot water heating to be facinating.

c.t.kay

try tundstall associates, at woody@tunstall-inc.com,for parts or trv valves.