Heating Zone

[garnetlake]

Greetings, is there anyone experienced enough to let me know if they have ever drained down a heating zone to replace a baseboard unit and then restarted it? I understand that I have to shutoff power, close return line and then drain the zone through a hose. I am not sure about the cold water valve that feeds the heater though. Will this automatically replenish what I remove? Do I have to shut this also? I guess the other question is what is involved once the unit is replaced. Does the zone automatically recharge with water once the valaves are reopened? Any help guys greatly asppreciated!

 

[Jwray]

No expert, but...

I'm no expert, but have some limited experience with my hot water radiator system.

I wouldn't open up the system without turning off the make-up water valve. If the sytem pressure drops it's going to try to replenish the water.

When you hook everything back up you will need to bleed the air out of the portion you drained. I would try to get as much of the air out before you startup the system. You should be able to do this by opening the bleeder valve on the baseboard usint and opening the make-up water valve (you should then leave this open).

You may have an override type lever on the makeup water valve that basically bypasses the pressure valve and lets water into the system at the city water pressure. Make sure the furnace/circulator are OFF before you open this. Also, make sure the bleeder valve is open before you open the override. You really need too people. One to run the bleeder valve and another to run the override. Once you get water from the bleeder valve you need to yell to the override guy to close the override BEFORE you close the bleeder valve. If you don't you will probably pop the T&P valve on the boiler. I learned this the hard way and made a wet mess in my basement. When you think about it it makes sense. The city water pressure exceeds the T&P valve setting.

After this you should be ready to start up your system again. You will probably need to continue with the bleeding as the system runs unless you have some sort of in-line air separator. In my experience any time you open up/drain the system it takes a while to get all the air out. It may be a bit easier with straight fin-tube baseboard than with CI radiators as there are less places for the air to "hide".

Hope this helps. Again, I'm not a pro, but this has been my experience.

Good luck with your work.

Joel

 

[Sponsor]

 

[hj]

zone

Draining the system is fairly simple. Just shut off the water feed to it, open the drain valve after connecting a hose, and then open something to let air into the system, possibly by cutting the existing baseboard pipe. Getting the air out of the system after installing the new baseboard is what can get tricky, and since there are many ways that it can be done, but only one right one for your system, (and it depends on how the pipes were installed), we cannot give you a specific way to do it.

 

[garnetlake]

Draining zone

Hey guys thanks for the advice I certainly appreciate it. I was not sure of the cold water valve but now you have straightened me out. I actually have an oil fired furnace with a mix of cast irion baseboard and vertical heaters. The verticals have unions on them and I was going to take out a tiny unit in a small bath and just bridge or close the loop with a hunk of pipe. To do this I need to drain the zone down enough to cut off the union ends and sweat a 2' piece of copper in there. What I was not sure of was how the zone fills back up again after I remove the 3 or 4 gallons of water. I actually did it a couple of years ago but the heating guy came and started it back up again. I am pretty good with bleeding it so I will give it a shot. Someone told me you have to charge the system back up with a garden hose before starting it but from what I gather from both of your posts this will be done automatically once I open the fresh water valve when the system is closed back up. Is this correct. Thanks so much for your time. Is this accurate?
GB

 

[Jwray]

Refill

Based on my experience sounds like you are on the right track.

If you have to drain down pretty far (i.e. the work you're doing is on the first floor of a two floor house) the refill will go very slowly if you don't use the override I mentioned. In fact I wasn't able to get my system to fill completely on the second floor until I discovered how the override worked.

BTW don't forget to use a dielectric fitting of some sort if you are putting copper in between 2 pieces of iron pipe. Also, if you have access to under the floor you may want to cut back the pipes to the point where you can splice in your pipe under the floor and out of site.

Finally, I think it may be a code violation to have a bathroom without some source of heat. Make sure enough heat can get into that room to keep the pipes (not to mention anyone getting out of a nice hot shower) from freezing. If this bathroom is on an exterior wall you may really want to think twice about removing the heat from it.

Joel

 

[Jadnashua]

The makeup water fill valve will open if the internal pressure is less than the setting on the valve. Once you close up the system again, it will have some air in it. That air will get pressurized. Eventually, that air will (should) get purged from the system, but it will go faster ifyou purge the air after closing it back up. If you can open a bleed valve until all of the air comes out, you can speed it along. There are two types of air valves that I'm aware of (I'm not a pro) - one type usually sits near the top of a storage tank and has a float mechanism that lets air out when it accumulates in the tank. A second type, one brand is Spirovent, is put in-line. It has a mechanism to "comb" air out of the stream of water that passes by - once enough accumulates, it vents it using a float valve system. If your system does not have the second type in it, then there will be some air trapped in the water as it circulates. Air in a closed system is not a great thing. It can take several bleeding exercises to remove all of it if you don't have the second type in your system. Oxygen is required to make rust on iron, or oxidation on other metals - the sooner you get it out, the less you have, the better it will be.

 

[garnetlake]

Wow, you guys are terrific. jwray, all of the pipes in the heating system are copper already. It's kind of a weird setup as it was the builders home in the development. He put all kinds of things in here that the tract homes don't usually get. The lines have unions sweated on them so I can cut them off under the floor and bridge it pretty easy. Still not sure what the overide is. I am on the east coast and maybe the plumbing here is a little different? Is this installed on the cold water line or somewhere else? I have a regular gate valve that I can close that feeds the heater. Once closed I don't think anything else can get into it. I am putting heat in it just not the hot water. There are new approved heat panels that you can hard wire into a theromstat that I am going to try. That plus a heat lamp in the ceiling. jadnashua, thanks for your input as well. This is how my system is setup. There is a gate valve with a bib above each circulator and an inline valve below it. When I do a normal bleed I close the valve below the circulator and open the top one with a garden hose in a 5 gallon pail until all the air comes out. This sound about right? I'll let you guys know how things work out. I actuaaly just got done witth a window and have to shingle before the freeze here.
Cheers Guys
GB

 

[Jwray]

Override

On my system there is a cold water line that feeds into the hot water heat plumbing to provide makeup water. The cold water line has a gate vavle to cut it off from the system completely for situations like we have been discussing. after the gate valve there is a pressure sensing/backflow preventer valve. This valve only allows water into the heating plumbing when it senses a drop in pressure indicating that some water has been lost (i.e. via bleeding the system, a leak). The pressure sensing valve has a bale type handle (like on a bucket) that is normally flat along the pipe. When this handle is lifted up at 90 degrees to the pipe is overrides the pressure set on the valve and allows water into the system at about the full flow of the main cold water line. The valve is labeled to only use with the boiler off. As I mentioned earlier I also discovered that you need to have some bleeder valves open as well or the city water pressure will pop the T&P valve on the boiler. I was not able to get my system to fill fully on the second floor without the boost of the extra water pressure.

Hope this gives you a better idea of what I was talking about.

 

[garnetlake]

Heating Zone , funny story

Guys, funny story about the heating zone. I got tied up doing other stuff in my construction and was about to remove the heater this week. I was still all worried about shutting down the zone and last night playing darts with the kids downstairs my daughter says there's a leak in the ceiling. Sure enough a bleeder on one of the heaters was dripping pretty good, all corroded. I went home drained it down like we discussed, changed the bleeder and restarted the heat in about a half hour. It's 15 degrees here now but I had no choice. Here I was all worried about leaks and trapped air taking out the heater and this went 1-2-3. Go figure. Now I can pull the heater without all the stress plus change all the bleeders in the bargain. Thank you guys for the help. By the way, there was shutoff for the refill line. I heard that running so just closed it.
GB