Bleeding Hot Water Heating System


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Old 01-23-07, 01:56 PM
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Bleeding Hot Water Heating System

I can't figure out how/where to bleed.

There are 6 zones, each with it's own zone valve, thermostat, and supply pipe. But there is only one return pipe.

The only place I see for bleeding is on the single return pipe.

But shouldn't I bleed at the highest point in each zone?
 
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Old 01-23-07, 06:51 PM
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Bleeding

Unless you have radiators or convectors, bleeding/purging at the boiler will work fine in most cases. Start with the lowest loop in the house & closest to the boiler. Make sure all thermostats are turned all the way down except for the loop on which you are working. It should be turned all the way up. Do only one loop at a time working your way up the house & away from the boiler. Why do you want to bleed the system? Introduction of fresh water should be kept to a minimum. If only having trouble with one loop, do only that loop.
 
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Old 01-29-07, 08:46 AM
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Hi Grady, thanks for your help.

I want to bleed because there is some sound (pinging like) I am hearing, and I am guessing that has to do with the trapped air.

I have baseboard radiators. Does that mean I should not bleed the system.

Also, outside on one place on the return pipe, I can't find any place to bleed anywhere in any loop. (In other houses, there usually is a place on one end of the radiator where I can bleed with a key or a flat screw-driver.)

May be you are saying I should close all loops, open one loop at a time, and bleed at the return pipe. Is that so?

Also, am I better of waiting until end of upcoming summer to bleed? Because I will be restarting the boiler and adding fresh water at that time anyway?

Thanks.
 
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Old 01-29-07, 07:43 PM
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Pinging sound

That sound is completely normal. It is caused by heat expanding the thin metal. After while, you'll get used to it & think of it as a good sound. The sound of HEAT.
 
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Old 01-30-07, 07:12 AM
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dance987

There are a several startegies for addresing those noises. Remember that these are caused whenever the HWBB have to change temps rapidly,

The easiest is not to use a setback t-stat or if you do to minimize the amount you set it back. The water gets very cold throughout the setback period and then it gets hammered to get back up to temps. If your house is well insulated you may find that you could set you temperature just slightly below your occupied temp and feel more comfortable because your house will reach an equilibrium of sorts. Everything in your home heats and cools at different rates. Setback creates a bit of discomfort as the body senses this. The slightly lower temp could offset the lack of setback. Setback saves most in poorly built homes that are underinsulated or drafty or both.

The second way is more involved. It would entail getting an outdoor reset controller. This controller would modulate the water temps so that they are only warm enough to heat the house given the temps outside. On milder days, milder water would hit it. This is far more expensive but does provide savings and much better comfort.

The third would be to try and reduce the number of zones. These create small loads that go off and on more frequently and randomly because of internal gains, them affectring one another. If all of your HWBB is balanced on a room by room basis, the simplest thing would be to have it all on one zone and run the circ continuously. Minimal noise that way.

You can try any of the above or any coombination of the above or do as Grady says, start noting just how beautiful and warm those cute little pinging noises can be.
 
 

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