Adding a new baseboard radiator

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Old 11-05-13, 08:31 PM
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Adding a new baseboard radiator

I have been trying to read all that I can find out about the procedure to add a baseboard radiator to our existing system, but I am getting confused. I hope that someone can point me to someplace to get the correct information, or help me understand the steps that are needed.

So, we just bought an older house that was built in 1965. It has the original Weil McLain boiler and hot water baseboard radiators. The previous owner did some remodeling and removed the radiator from the master bath. It needs to get replaced before it really gets cold.

I called a couple of local companies and had trouble even getting anyone out to even give an estimate. They just wanted to replace the system. The couple of estimates that I did get, were really expensive, pushing nearly $1000. So, being handy with most things around the house, I figured that I can do this myself and save some money. I ordered a new Slant Fin register and valve for about $80. So far so good.

This should be fairly easy (I think). The water lines are directly below the bathroom in the basement. Since there was previously a radiator installed, there are already one way flow valves installed with the feed and return capped. I gather that I just need to drain and fill the entire (single zone) system. That's where I am lost. Where can I find specifics on how to drain, fill and bleed this system? Being auto fill, do I just turn the water back on and let the auto valve do it's thing? What about the expansion tank, do I drain it? How do I get all of the air out since there are no bleed valves?

Thanks for any help anyone can offer.
 
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Old 11-05-13, 09:21 PM
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It sounds like you have a monoflo system(supply+return in same line with special tee or tees.). If this is the case to drain your system, shut off the main water to the boiler and drain the water out from the boiler drain.If you have a steel expansion tank if it all doesn't drain with the system you can drain that too. You will probably pull a vacuum on the system so you can open up your pressure relief valve to empty. When draining your tank drain it fully or you'll have problems later. There should be some kind of vent on there or you will pull a vacuum. When you're done you refill and bleed. With a momoflo system you must bleed every radiator. They should all have bleeders on them so make sure you put one on your new rad. Fill system to between 25 & 30 lbs and bleed each radiator checking pressure as you go. When pressure gets to about 20 lbs refill. When done drain excess water from boiler to about 15lbs. One more thing, check your bleeders on your rads and make sure they work(not painted or stripped) and change before you refill. This should get you started. Good luck.
 
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Old 11-05-13, 09:27 PM
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there are already one way flow valves installed with the feed and return capped.
Can you show us a picture of these?
 
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Old 11-06-13, 11:13 AM
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I'll get some pictures of the system tonight. Thanks.
 
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Old 11-06-13, 11:22 AM
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I'll get some picture up tonight after I get home.

You are correct, it has supply and return in the same line. The main line is 1in. copper with 1 way a 'tee' before and after each radiator so that each radiator is in parallel to the main.. Each radiator is fed by 1/2in. copper tube from the tee.

Each radiator has a 1/2 turn flow control valve on the input side but I do not believe that there are any air vents on the output side. I'll verify that tonight.

Thanks for the info.
 
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Old 11-06-13, 05:53 PM
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Mono-flo systems can be a bit more difficult to purge air. As has been suggested, jack up the pressure to 25 psi. With a mono-flo system, there should be a bleeder on each baseboard or radiator unit. If you have zone valves or plug valves, shut all of them except the zone you are trying to bleed. Then try it with and without the pump running. When the system was originally installed, that was the worst condition - and the air was somehow removed.
 
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Old 11-06-13, 08:25 PM
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OK, these are the one way valves. As you can see, the lines are capped that previously went to a radiator that the previous owner removed. I hopefully can just drain the system and then re-attach these capped lines to a new baseboard radiator. I have more pictures in another post.
 
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Old 11-06-13, 08:40 PM
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So you can see from the images below, the parts to my heating system. The first 2 images are of a radiator valve and elbow. As you can see, there is no air bleed valve.

Next, you can see my pump. Below it appears to be the only drain valve, except for the one on the expansion tank. Is the one below the pump the one that I use to drain the system?

Next is the expansion tank. One end has a shutoff valve, the other end a drain valve. Do I drain this or just leave it alone during the drain/fill?

Next, I assume that the shutoff valve is the input water. Do I just turn this off to drain and then on to refill?

And finally, the last photo I think is the auto fill valve. The thing on top would be the air vent, right? When it comes time to refill, would this be completely automatic?

As you can see, there appear to be no air vents other than the auto valve. Can I just turn the water back on an have the system refill and balance the pressure automatically? There has ben mention of putting slightly higher pressure in the system to force out the air. How do I override the auto valve?
 
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Old 11-06-13, 08:41 PM
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Yes you can, just make sure you have the supply going to the supply on the heater. The air vent must be on the return side so the water goes through the unit and then out, not up the supply and out. If that makes sense. The air vent on the unit in the pic would be on top of the unit on the return side, not on the pipe. Air always rises and comes out the top. Its the only way to bleed a monoflo system.
 

Last edited by spott; 11-06-13 at 09:16 PM.
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Old 11-06-13, 09:30 PM
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Yes, that's the drain valve. Shut the main water off before the autofill( the last pic). Drain the tank at the same time through the boiler and open up the drain on the tank also with a hose to let air in to drain completely. When your done turn on water. To raise pressure to 25lbs. to bleed, loosen nut on autofill and turn screw clockwise. You'll hear water coming in. Maintain pressure while bleeding. When done set valve back to 15lbs. and drain off excess water to 15lbs. Check rad. air vents to make sure they work while system is down.
 
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Old 11-08-13, 02:46 AM
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Thanks everyone. I think that I understand enough now to be dangerous. The new radiator arrived yesterday from Pexsupply so I am ready to go.

One more question, can I use Pex tubing to attach the new radiator?
 
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Old 11-08-13, 03:16 PM
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can I use Pex tubing to attach the new radiator?
Sure... but you MUST use the 'correct' stuff. It has to be made for heating systems and include an OXYGEN BARRIER!
 
 

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