How often should a steam boiler be cleaned?

Mike_D

I started the heating season with a new Slantfin boiler (in a one pipe system). I am under the assumption that as soon as the water line starts moving more than +/_ .5" or when the water starts looking rusty it's time to clean the boiler, but for many weeks it took only 3 or 4 days before that would happen. By now I can get about 2 weeks and if I do a quick skim it adds a few more days before it looks like it needs cleaning again. I'm wondering if this is normal, because the VXT programable water feeder I have will really never be able to track water usage if I'm cleaning and/ or topping off the water level manually as often as I'm doing.

Thanks,

Mike_D

Steam_Starter

Cleaning, Cleaning and More Cleanine

What I found after my installation was that it took me over a month to get all of the oils, sealers, etc out of the boiler via skimming to get a clean sight glass and under an inch of bouncing. Some take longer, some take less; all depends on contaminants in the water.



I would not really try to calibrate water consumption until after it is clean. Unless you see a glaring level problem overnight or within a couple of days.



Cleaning is the key; if you skim it right then cleaning afterwards entails clearing the LWCO weekly and blowing down the boiler about every month depending on usage.



Good luck,



Jim

Paul48

Read

your manual. It would seem your boilers were not started correctly. They should have been thoroughly flushed.

Mike_D

re: Read

thanks man, you're the best...

Mike_D

Re: Cleaning, cleaning & more...

thanks Jim

crash2009

Wet return

Yes, I think that it is normal for a new boiler to get dirty for a long while after just being installed.  As previously mentioned, your new boiler is sending steam to places where steam has not been for years.  Condensate, returning to the boiler, is carrying all this oil and sludge from the old pipes, back into the boiler.  The rough diagram below illustrates  where oils might be resting before they return to the boiler.  You may or may not have all these cleaning valves installed, but hopefully your installer left you some way to clean the wet return.  I beleive this is where your dirt is coming from. 



Do you have some way to drain the wet return? 

Mike_D

Re: Wet Return

Thanks Crash,

I installed the boiler myself (with good advice) so I have been cleaning it through a tee at the return with a copper wand I made with a 90 bend at the end. You are right that the return pipe was dirty but I flushed it with hot water so many times from the A dimension until it ran clear (I even banged on the pipe to loosen up). I am concerned that all this cleaning will cause the boiler to develop scale. I am also wondering if suppling hot water to the feed would have less oxygen content causing less rust & scale to form?

Long Beach Ed

Feeding with hot water?

Don't feed with hot water. 



You'll find that the valve in your automatic feeder will foul. 



That's guaranteed.  Don't ask me how I know. 

Mike_D

Re: feeding with hot water

Thanks LB Ed!

crash2009

NO

  Do not use the hot water to feed the boiler.  I don't have any direct experience like Ed, but I have read about all the reasons not to use the hot for a feed.  Chemical re-action mumbo jumbo.  You gotta be a scientist to explain it.



Getting back to your wet returns.  You said you flush them with hot water, would I be correct in assuming, you fill them with hot water before you start the boiler.  Is it possible that this "unconditioned water" is contributing to the dirty boiler water?  Have you tried to drain, flush, drain, the wet return and let the boiler fill the wet return with condensate?  In other words, drain the wet return completely, then steam the boiler.  The condensate will be steam-turned to water, therefore conditioned.  Another trick is to steam clean the return.

Mike_D

Re: NO

Crash,

I have only fed the hot water to the boiler drain cock through a hose from the wash tub, but is that alright because I have bypassed the feeder?

I did drain & refill the return a few times with hot water but have not done that for a while. The return seems to be clean the last few times I drained it. Also, I put a magnet in the return to pick up sludge before it gets to the boiler and there is less sludge stuck to it each time I clean. I have still been filling the boiler with hot water. I'll think about steaming the return...

Mike_D

ChrisJ

hot water

As far as I am aware the only reason to not feed with hot water is auto feeders.  I believe its perfectly fine if doing manual feed only.



I had considered piping my boiler this way but decided to run from the cold line due to simplicity.

Ron Jr._3

Is there a shutoff valve on the return ?

You want to isolate the return pipe from the boiler so you can flush out all the crap that was in the pipe . If the system was particularly dirty and has old wet returns we add a mild liquid cleaner ( usually 8-Way ) , and let the system steam all the time we're purging the returns . Some come clean after 10 to 20 gallons are purged out ( usually copper returns ) . Some take 50 or more . I'd  say that if they don't stay clean for at least a season or 2  after so much water being purged I'd recommend new returns . 

Mike_D

Re: hot water

Thanks Chris

Mike_D

Re: Is there a shutoff valve on the return ?

Thanks for that Ron,

I didn't install one but I will because I can see how it will help.

crash2009

Looks like

 I jumped the gun on the hot water thing.  Sounds like the general concensus is that it's ok to use the hot water as a feed for the boiler, providing that the hot does not go through the water feeder.  I can't remember where I got the idea that it was a NO NO period?

crash2009

Mike,

  When I was re-piping mine, I must have researched the subject here on The Wall.  If you do the same you will likely find out that the jury is out.  Some are "for" and others are "against" feeding the boiler with hot water.  Some of the reasons against are: 

1-Some (maybe all?) boiler manuals say to use the cold (warranty issue?)

2-If there is a water softener installed now or in the future, the water in the hot water tank will become "softened" softened water is no good for a boiler.

3-If the hot is run through the auttomatic water feeder, the feeder will become fouled. 

After reviewing my research, I will have to say that I am against using the hot water line for any reason whatsoever asociated with the boiler or it's piping. 

Crash

Mike_D

Re: Mike

Thanks Crash,

I'm not going to feed with with hot water. I am going to clean the boiler with hot water because I want to be able drain it (hot, while it's in use) and flush it with out immediately while minimizing the thermal shock to the block which seems to be the case. I usually flush about 10 gallons of water through to make it clean and it still feels quiet hot. But can I feel comfortable to immediately fill it with cold water or should I wait a bit?

ChrisJ

wow

I'm over here trying to run as little fresh water into my boiler as possible, and your over there setting up to run 10+ gallons at a shot through yours.



I don't know about good that is in the long run being used for cleaning or not.  I'll admit, skimming I ran probably close to 60 gallons through, but since then none.  Yearly blowdowns I don't expect to use more than a few gallons.

cn30

hot water

My understanding is that hot water holds more minerals in solution than cold.

ChrisJ

hot water

If the same water you are using for cold is going into a waterheater and being heated, not exposed to anything else and then sent to the boiler, where it will again be heated how could it possibly have any more minerals in it?

Al Corelli_2

Minerals?

Wouldn't hot water tend to have less minerals? When the water is heated aren't many of the minerals precipitated out and left in the form of crap in the bottom of the heater?

Mike_D

re: wow

thanks chris,

It is the opinion of many here that the boiler be cleaned monthly. The manual is vague as to what a monthly cleaning should be. The water starts looking rusty & surging after about 2-3 weeks even with a couple quick skimmings (maybe 1-2 gal. thru). If I flush the dirt out from the bottom with my spray attachment, it usually takes a second 5 gal. bucket to look clean which was essentially my original question: Am I cleaning the boiler too much?

It doesn't make sense to me to have this VXT programable water feeder designed to track the water usage if I'm refilling to the waterline a few times month; the tracking feature is useless with all this cleaning...

Mike_D

re: minerals?

thanks Al,

this was what I was thinking but I'm only smart enough to be dangerous...

cn30

minerals

Hot water does hold more minerals in solution and/or suspension than cold. Google it if necessary--it's not my thought. If hot water runs through a pipe with deposits built up inside it will dissolve and carry on more of that than cold water will.

Luv'nsteam

VXT by-pass and

Installation valves - do you have them? These would allow you to run the water to clean and blow-down, but not register on the VXT.



http://www.hydrolevel.com/pages/pdf_files/vxt24_opt.pdf



Thank you,



Mike

Luv'nsteam

Minerals in hot water

Most minerals become more soluble in hot water. Think about salt in water: the hotter the water, the more salt will dissolve in it. However, there are two minerals, I think, that actually become less soluble in hot water. These minerals are what is often referred to as 'lime'. As the water gets hot, these minerals 'fall' out of the water. I am not an expert or a chemist, but I do need to clean my water heater every six to eight months in order to keep it in good working order. This entails vacuuming it out with a wet vacc after draining.



Google this to be sure, but I think 'lime' is manganese or magnesium and calcium. I also recall, a water softener removes calcium and magnesium or manganese, by sodium ion transfer: basically, the salt replaces the 'lime'.



I too wanted to hook up my feed water from the hot supply, but I seem to recall reading something from Dan about automatic water feeder MFG's saying not to because of the reason LB Ed mentions. And now that Crash provided his research results and reasoning, I will also use the cold for feed water.



Thank you,



Mike

ChrisJ

hot water

This may be all true, but everyone seems to be forgetting something.

The hot water you are feeding, came from the same cold water you would be feeding. It contains no more minerals than the cold water did.



In fact, if you say you have to clean your water heater this suggests the water coming out of it would have LESS in it. Everyone is also forgetting that your boiler HEATS the water, it doesn't stay cold. There was also a thread on here which mentioned using a water heater combined with a deaerator (whatever that is) to treat feed water.



Maybe there is some small detail I am forgetting and if there is I am sorry.

Luv'nsteam

Less minerals in hot water

Yes, there are less minerals in my hot water because the 'lime' falls out when the water is heated in the water heater. This is why I need to clean it out so often - the minerals build up in the bottom and build up and build up and eventually they coat and then surround the lower element, decreasing its life span greatly. Then my wife hollers because she had a cold shower and soon after, if I ignore it (I have in the past, to my own peril) the lower element gets eaten away from the minerals and fails. I have dealt with this for 14 years, have replaced the lower element three times, and with high quality alloy elements, along with new anode rods and since I began cleaning it often, I have a much longer life of the elements.



Yes, all the water in my house starts from the same place - the cold supply from the street and it is very hard. But being heated in the water heater, is sort of like a filter for calcium and manganese or magnesium (which ever one it is), so the hot water is actually softer than the cold.



Because there are less minerals in the hot water, is the exact reason I and likely others, have thought about feeding the boiler with pre-heated water. In this way, in theory anyway, there would be less minerals, ie: lime, in the boiler, thus preserving its life span.





Thank you,



Mike

Mike_D

re: VXT by-pass and

thanks Mike,

I do have the by-pass valves and I understand about running the water clean but you're missing the point. If I'm skimming and subsequently refilling to the water line even once a month, (assuming the boiler should be blown down once a month) then refilling what may have leaked elsewhere in the system is not being accounted for. For the VXT to keep track of the makeup water over time, you can't be cleaning/ refilling for at least a month. So again, when and how often should you clean the boiler?

Luv'nsteam

How often to clean

The boiler? Honestly, Mike, I am not sure and that is the reason I am reading this thread. When I finally fire up my new boiler, I will also need to clean it. I do have a slight advantage, as I also replaced all of my returns, so the only mud will be from any old horizontal runouts and from the radiators. And of course, oil and whatever else I added during assembly.



I do not recall if it is was in a thread on the wall or in the TLAOSH, but, Dan talked about taking some water from the bottom valve under the sight glass and boiling it on the stove. The way the water boils apparently tells a lot about the condition of the water. If it does what is desired, I presume it is clean enough. Also, in the back of TLAOSH is several cleaning instructions from a couple different boiler makers, maybe your answer can be found there?





Thank you ,



Mike

Mike_D

re: how often to clean

Mike,

I also read TLAOSH and it helped me alot, but I think part of my problem was that I used Rectorseal #5 thread sealant. I read somewhere else that oil based thread compounds should not be used in steam systems and I have witnessed tiny oil spots oozing from the joints on threads I know that I cleaned well before assembly. I read this after most of the near boiler pipe was in place. Also, I inherited a system that had been grossly neglected. I didn't do the stove top method because it was obvious to me that it was fouled after the water line started moving up & down by more than +/- 1/4" (+/- 1/2" tells me it is surging and it was easy to prove it by closing the bottom sight gage valve & opening the drain petcock). Water will spill over the top tapping & flow out the petcock; not steam.

Charlie from wmass

Hot water off the same line as cold water

has less minerals in it. The minerals are left behind in the water heater. Hot water eats washers in the feed valves and seats in auto feeders, that is why cold water is used to feed boilers. On large boilers with manual feeds and tankless heaters and people prone to fast filling, thus cracking the boiler, I have fed the boiler with hot water.

Luv'nsteam

Heat damage to seal

It would seam, then, that the heat is the issue for the seal(s) in the auto feeder, is that a correct statement? If heat is the problem and if a reduction in mineral content within the feed water is indeed, healthier for the boiler, would it be advantageous to still use hot water, but cool it some how before going through an auto feeder? This seems to be a lot of additional work and cost for heating the water only to cool it, but if it works as suggested, would the benefit to the boilers life span be worth it?



Thank you,



Mike