Isolating a zone on Boiler

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Old 09-12-12, 08:15 AM
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Isolating a zone on Boiler

I have an older boiler , 5 gallon hot water combination . I want to replace all the lines to the first floor radiators . The old lines run well below the ceiling , and are an eyesore as I want to finish the basement . Alos , the woman who had the house did no maint , and all the valves at the rads leak if you so much as look at them . Question-what is the procedure to isolate the main zone(2 zones , 1up and 1 down) so I can remove the old pipe , replace with TheramPex and change all the valves . I will also need to remove a rad , as it sits where a new french door to outside will be going . I have included pics , the boiler , 2 zone pumps(no shutoff near the pumps) , the two returns from each zone with drain valves and the domestic hot water supply , which I wont be touching-had them adapted for pex already .
Thanks in advance.
 
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Old 09-13-12, 09:34 AM
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the inlets/oulets to the pumps dont have any isolation valves.
your boiler also has a tankless coil for hot water right?
you have a bit of a dilemna - in order to do this, you need to disable the boiler, leaving you with no hot water temporarily for the wife n kids, so you need an 'outage' plan

1. power off the boiler, check there is no voltage, unwire any pumps or controls/relays that you need.
2. let it cool down before draining this might take some time
3. isolate the water supply, bleed off any pressure
3. drain the all water out - eventually all the radiators will empty out as well, but you will need a vent open up high at a radiator to help allow water drainage, if rads are not fitted with vents, you may need to cut or unsolder a pipe/fitting to vent it to atmosphere. opening the relief valve on the boiler will also help.
4. exchange your equipment and fittings that you need to do. install valves to isolate the pumps, etc.

if you do the vavles for the pumps, also fit drain points for each zone as well.
Also, if you install the valves for the pump, then you can get your boiler up and running to provide domestic hot wate, but the boiler will need to be refilled with water prior to firing.
This can buy you time to finish off the rest of the piping while keeping up the domestic hot water services for the wife and kids. YOU NEED TO MAKE SURE THAT THE VALVES & PIPES ARE LEAK FREE AND HOLD TIGHT.
 
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Old 09-14-12, 07:28 AM
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Thanks , the one issue I have , I have always had gas boilers , except for the last house-and it was such a problem-constantly getting air in the systym , and shutting off-had one guy there 6 times in a week , don't want that to happen again . The question is about re-filling the boiler and starting it again , how to avoid air in the systym . All the rads are either baseboards or older 1970's baseboards that are reccessed into the walls , so no vents . With pex i can proably run most of the pipe ahead of time , if I dont finish I can put a pex plug in the line till later , as long as that dosn't mess up the domestic hot water .
 
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Old 09-14-12, 10:26 AM
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The way to get rid of most of the air when re-filling your system is to purge the loops. Those blue-handled drain (purge) valves are there for that purpose.

Purge one loop at a time.

1. Attach a garden hose to one of the blue-handled drain valves and direct it into a floor drain (or use a large bucket.)

2. Close off the green-handled isolation valve located directly below that drain valve.

3. Manually open up the automatic boiler water fill valve using the metal lever located on the top. (The auto fill valve on your setup can be best seen in your last pic, it is located on the far-right, in between the yellow-handled valve above and the green-handled valve below). After opening the fill valve, immediately open the drain valve to allow the fresh water to circulate through the loop and out the drain valve.

4. When the water coming out of the drain valve no longer contains any air, close the drain valve and immediately close the fill valve.

5. To purge the other loop, repeat steps 1-4.

Keep in mind that, after purging the loops, you will want to see about 12-15psi left in the system. If necessary, you can either add or remove fresh water to get it to that level.

You might consider adding vents to the radiators, if feasible. Keep in mind also that, depending on how your system is piped, removing one of the radiators might negatively affect the performance of the entire loop.
 
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Old 09-16-12, 07:13 AM
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Thanks for your help , I will give it a try this week.
Jim
 
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