Building mechanical/utility room relocating modifying pipe work


Old 05-10-12, 08:14 AM
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Building mechanical/utility room relocating modifying pipe work

I am in the planning stages of finished the basement around the hotwater boiler and other utilities.
With this means cleaning up the pipe work, and removing the left overs from past retrofits and upgrades (old unused preasure tank still attached to the system, capped tees, etc). I'm also looking to add a gauge or two to help keep a better eye on things (and the geek inside loves gauges). Currently there is only the one dual function gauge (preasure/temp) attached the the boiler, which I question it's accuracy.
I'm still in the pre-planning stages currently, but do have a couple questions.

1. For the replacement pipe, my better judgement says stay with copper (entire system is copper), but my wallet doesn't agree. Bad idea mixing materials?

2. The current setup has the fresh water feed connected on the return end going into the boiler. I thought I remember reading somewhere that it was better to connect it at the boiler exit to prevent shocking the system with cold water. Should I relocate the freshwater feed to the boiler's hot side?

3. Gauges... Currently have a dual display (temp/PSI) on the boiler, but don't trust it. I'm thinking of adding a set (temp/PSI) after the presure tank (before the zones seporate) and maybe a set (temp/PSI) at the return end of each zone (temp/PSI). The set on the zone returns may be over kill, but I'm thinking the temp and PSI readings could be indicators if there is leak issues or if one floor is burning off a lot of heat compared to the other (this is an old house/system). I'm also looking to include an hour counter for each circulation pump which on a monthly basis, could give me warning signs of I should review the t-stat schedules and or home insulation. I'll be putting these gauges into a pannel similar to the systems I've designed/worked on in process plants.
Anything else I could/should monitor?

4a. Circulation pump orientation.... Currently my two pumps (one per zone) are mounted horizontally at the hot side of the zone (exit fom the boiler, after the expansion tank). I've seen plenty of pictures of the same pumps as I have, mounted both horizontal or vertical, does it make a difference? One better then the other?

4b. I've also noticed the circulation pumps being placed after the expansion tank on the hot side of the boiler, and on the return side. My current setup has the pumps installed on the hot site and the begining of the zone. Personally I think the pump on the hot side would be better, but with it on the cooler return side, it would be exposed to cooler operating tempurates (exdending their life maybe). Is there a prefered end of the zone to place these pumps?

5. Check valves... I believe (need to confirm) that my system has one check valve, installed after the two zone return lines meet back up, but before the freshwater connection. Should there be more and where would they be located if properly installed?
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Old 05-10-12, 10:12 AM
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1. Pex-AL-Pex is my preffered pipe when we relocate supply and return line, its construction limits thermal expansion and therefore reducing noise associated with the expansion and contraction tendancies of PEX

2. The fill point has to be at the point of no pressure change, which is the suction side of the circulator and where the expansion tank must be also. Remember these days we pump away from the boiler.

3. Temperatures guages are cheap and can provide nice troubleshooting / set up aides. Too many pressure guages might get you into trouble as pressure change throughout the system depending on where you are getting your tap point from.

4. see item 2
Pumps these days do not care about the temperatures in hot water boilers, 200 F will not hurt them in any way.
5. Check valves are need to prevent thermal migration, mostly in the system you have. They are also flow direction control devices. You put them where they are needed, and no more.

Remember , if it ain't broke don't fix it.
Old 05-10-12, 10:40 AM
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Be careful in removing capped tees, sometimes they are there to facilitate maintenance. You are wise to question the combined temperature/pressure gauges as they are generally of lower quality. I prefer separate thermometers and pressure gauges and then you can get the level of quality that you desire.

1. Generally, yes, it is a bad idea to mix materials but depending on where you want to change and what you want to change to, it might be acceptable.

2. Hot water systems should not need much (really none) "make-up water" if they are tight. Having the make-up connection in the return line is acceptable because the make-up is done by a reduction of system pressure and that rarely happens when the boiler is firing, or even in the upper range of its temperature profile. Even then, the make-up will be blended with the return water so you won't be adding cold make-up.

You MAY be mistaking this with having too low of temperature on your loop returns. This is a different issue.

3. You really only need one pressure gauge, on the boiler. Adding one on the circulating pump discharge would be the only other place that I would recommend. Use a pressure only gauge (not a combination pressure/temperature) of at least 3 inch diameter to get some accuracy. Highest reading no more double the Maximum Allowable Working Pressure (MAWP) of the boiler as stated on the nameplate or a minimum of 1-1/2 times the set pressure of the safety valve. Pay a little extra for a high quality gauge. Ideally you would have the gauge mounted away from the boiler to isolate it from vibration and then connect to the boiler with copper tubing.

If you want to spend money and exercise your instrumentation skills then get a pressure transmitter (range as stated for pressure gauge) and a digital display. I prefer current (4-20 mA) transmitters and displays over voltage models as they are inherently more immune to electrical noise. You could even use displays with high/low setpoint switches to control the burner action.

A thermometer on the boiler or boiler discharge is necessary. I prefer a minimum of a 3 inch bi-metal dial thermometer. Repeatability is far more important than absolute accuracy although the better the absolute accuracy the more I like it. Have at least one bi-metal dial thermometer and the rest can be RTDs or thermocouples. A return temperature thermometer is nice to make certain that you do not have low return temperature issues. RTDs or thermocouples on the individual zone returns that you can use portable (hand held) meter on might be fun or you could add mechanical thermometers. You could even connect the pressure transmitter along with several RTD or thermocouples to a data logger and upload to your computer periodically is you really want to be a nerd.

4a. The pump orientation depends upon what the manufacturer states in the instruction sheet. Generally the pump itself can be mounted in four different orientations but the motor should be horizontal.

4b. Circulating pumps should ALWAYS be mounted downstream of the expansion tank, ALWAYS! That stated, there are tens (or hundreds) of thousands of installations where the pumps are incorrectly mounted in relation to the expansion tank that work just fine. My first post on this forum was to explain that fact. We had a member whose system had the pump on the boiler return and while it worked okay initially when he expanded the system he had no end of troubles. It would have been a fairly big job to move the pumps so I advised him to merely move the "point of connection " of the expansion tank to the suction side of the pump and after fighting his system for months he then had a well-behaved system. Definitely made a believer out of him.

5. There should be flow control valves on each loop that has a circulator. Generally these are the only check valves necessary but sometimes you need additional valves on an indirect domestic water heater.

A few dozen pictures of your system would help.
Old 05-11-12, 11:30 AM
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Thank you for the information guys. For some reason I didn't get a notification of posts on this thread. Wish I had as I spend a few minutes over lunch sketching up a rough P&ID of the setup I am looking to go with.

The picture below is basically what I am looking at doing. For the most part (excluding all the extra gauges), this is my working system. I did not include all the capped tees, the old/unused expansion tank (connected in line with the current tank, just shut off with a ball valve). Also note that the tempurature gauge and presure gauge are shown attached, even though the actual gauges will be seporate units, but attached at or near the same point.

(Please don't beat on me for not using proper symbology, drafting is not part of my job description).
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I'll take the information below and make changes to the P&ID sketch where needed. I'll also go snap happy with the camera and post those as soon as I can.
Old 05-14-12, 07:15 PM
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Sorry about the delay on these photos.

This first one shows the mess of pipe work I am looking to relocate/clean up prior to framing the walls. You'll see the old unused preasure tank at the top and the newer expansion tank below it. The pipe near the bottom right is the return line to the boiler.
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This next picture is the fresh water feed and bypass. A couple redundant ball valves in here.
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This is the exit to one of the circulation pumps. As you'll notice, it is leaking. Only leak in the entire system as far as I can see. Don't think I'll be calling this pro to work on my system again.
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The following photo shows one of the capped tees. It is found on the return line of the main floor zone.
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The following photo is of the unused tank. It currently only contains air.
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Old 05-14-12, 07:30 PM
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Nice start, now add a couple dozen more pictures and don't forget to include the boiler.

I see things that I would definitely change, starting with the location of the boiler "emergency" switch. The capped tee shows no sign of having ever leaked so why does it bother you? The piping that goes "through" the corner of the chimney DOES bother me in that it could have structural repercussions. The only ball valve I see in the picture of the make-up water reducing station is the drain. The isolation and bypass valves are NOT redundant but show that the installer was thinking ahead to the time when (not if) the reducing valve would need rebuild or replacement. Some more pipe hangers are probably in order and that type NM cable is not installed in a workmanlike manner and should be addressed.
Old 05-15-12, 05:31 AM
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The pipe going through the corner of the unused chimny is not a pipe, but useless pink wrap insulation hanging down from the pipe above. Someone spent way too much time and effort wrapping that stuff and duct taping it off. Because of the heat at the boiler, the duct tape turned crusty and brittle and had let go.

As for the couple dozen photos... here is a start for you. I will try to post them in order as if you are walking around the system. This should help reduce orientation confusion.

This first picture, I am facing West. Looking at the side of the boiler with the hot line exiting the top of the boiler. The brick chimney to the right is unuses (was a wood heat house way, way back when) and the boiler chimney is sean just on the left edge of the photo. The gauge on the top of the boiler is preasure/temp.
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This next picture is of the boiler chimney. This takes a sharp 90' bend to the south and out the foundation wall.
You'll also see the burner head down near the bottom and just in behind the chimney is the braker pannel (why there).
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Here is a straight on shot of the boiler. One thing to note, the domestic hotwater attachment just to the left of the chimney in the photo is not used. The previous owner installed an electric hot water tank after replacing the coil for the second time within 12 months. If only he knew that if he fixed the water softener and maybe even cleaned the boiler, it might not have plugged up.
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Another shot of the boiler, facing North East. You can see the control box for the boiler mounted on the right (west) side of the boiler.
The piece of wood at the top right of the photo is where the braker pannel is mounted.
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This next picture is of the boiler facing East. You'll see the cold water return feed leading towards the bottom right of the boiler.
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This next picture is of the circulation pump shown in my previous post with the emergency switch tucked behind it. This is the input end with the control box tucked in behind it.
These control boxes and the emergency switches will be relocated to a better more accessable location and as far from leak potential areas as possible.
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This next picture is facing south. You'll see the currently used expansion tank in the top right corner, with the fresh water feed controls below it. In the middle appears to be a check valve (no markings) and the unused chimney on the left side.
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And finally, this picture shows the corner of the old unused presure tank (top right), and the control box for the circulation pump for the second/third floor zone. As you probably have noticed, pipe hangers are few and far between.
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So long story (and a number of photos later), you can see the mess I am trying to clean up and relocated.
Let me know if there are any specific areas I should post more pictures of.
Old 05-15-12, 05:38 AM
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the boiler feed is not at the expansion tank where it needs to be.
Old 05-15-12, 05:51 AM
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Originally Posted by TOHeating
the boiler feed is not at the expansion tank where it needs to be.
My understanding is the expansion tank is suppose to go before the circulation pumps, which in this case, the circulation pumps are located on the hot side of the boiler. I included this setup in my poorly drafted P&ID in post #4.

Am I mistaken?
Old 05-15-12, 04:35 PM
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For some reason I didn't get a notification of posts on this thread.
You'll only get a notification if you click the button "Thread Tools" at the top of the thread and click "Subscribe to this thread".
Old 05-16-12, 05:34 AM
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no you are not mistaken, but it looks to me from the pics and the drawing that the make up water enters on the return side of the boiler. It should always be installed at the oint of no pressure change, which is the expansion tank point.

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