insulation causing short cycles?

danmayer175

One-pipe steam. I insulated the 2" mains in the basement yesterday. Now the boiler is short-cycling - usually 4 minutes on, 8 minutes off. Is it possible the radiation from the un-insulated pipes was keeping things in balance? Do I need to downfire my boiler now?

I have a Burnham V7 boiler with 488 sf output serving 10 radiators that total 448 sf. I calculated the radiation of the main piping at 42 sf. Pressuretrol is set to cut in at 0.5 with differential of about 1.2. I have a Gorton #1 on the main, and Varivalves on all the radiators, except for 3 smallest which have Hoffman #1As. Thinking that pressure is the problem, I currently have all the vents wide open.

Abracadabra

Gorton #1 is not enough venting for a 2" main of any length. Also, what does the pressure gauge say? Hopefully you have something more useful than a 30PSI gauge installed.

gerry gill

I personally would not consider 8 minutes off to be short cycling..but thats just me.

danmayer175

It looks like I have enough room to install a Gorton #2, should I try that?

The 4 minute burn is the short part - it cuts out before any steam gets to the last branch, and no change in room temperature at the thermostat.

BobC

The fact you are cutting out on pressure before steam gets to the end means you need more venting, maybe lots more venting. One Gorton #2 for each 20 ft of 2" main would be best.

Bob

Mark N

What were length of your cycles before you insulated the mains? What is cutting off the burner? The thermostat, the pressuretrol, LWCO. What thermostat do you have? Is it correctly configured for steam. Let us know.

Jamie Hall

Those cycle lengths sound much more like an improperly set thermostat. Usually if a boiler is cycling off on pressure, it will restart very quickly -- a minute or two at the most -- as that is all the time it takes the steam to condense. Indeed in some situations the pressure will drop enough to restart before the post purge cycle of the burner finishes (oil fired).

So the first thing I would check would be the thermostat cycle setting or anticipator (note that a total of a ten to twelve minute cycle is typical for hot air...).

danmayer175

I never timed the cycles before insulating. I'm not sure what's cutting the burner - I haven't done a definitive test to rule out the thermostat - how would I do that?
I don't think the LWCO is the problem. I tested it once before and it activates at much lower water level than I currently have. The thermostat is a standard Honeywell dial with a mercury bubble.

Mark N

You never timed it before, so how do you know it is acting any differently then before? What is the anticipator set to? Is the thermostat level?

SlamDunk

The short answer is yes. I just experienced the same thing this week. My boiler is marginaly oversized (approx .10-15%) . But, my wife valved off a large radiator in an overheated room making the boiler even more oversized; however, it was unnoticeable during last heating season. Last week, I insulated some 60 feet of uninsulated 2" and 1-1/4" mains and now, I am short cycling (two minutes on; two minutesoff as opposed to 15 minutes on; thirty off or something like that).
I have plenty of venting. M wife insists on keeping the radiator off, wants me to peel off the insulation so we are back to normal. Nuts.

KC_Jones

"My wife insists on keeping the radiator off, wants me to peel off the insulation so we are back to normal. Nuts."
Ask her if she wants to start flushing money down the toilet also. lol

David Nadle

Don't remove the insulation. Get a TRV for that oversized radiator and your wife can dial in the temperature she wants. I would put at least one or two Gorton #2's at the end of each main and turn those varivalves all the way down.

SlamDunk

I do have 2, number 2 vents at the end of each main and they operate as intended. As far as flushing money down the toilet...The rad is in the bedroom and she is experiencing hot flashes and doesnt care. I'm sure you would appreciate that this is a difficult argument to win. I'd rather keep the peace.

We're in the south and it was relatively inexpensive to heat on steam without the insulation. I think the highest gas bill was around $175 last year which was the coldest on record. That goes in her favor. I might just peel off one 3' section at a time until the short cycling disappears.

Jamie Hall

I've said this before...

Short cycling is an unfortunate catch-all term, and is often badly misunderstood.

Sometimes it can be difficult to figure out what the problem really is, and in those cases a good low pressure gauge on the steam main can be very helpful.

What you are looking for is when the boiler cycles, and which control (thermostat, pressuretrol or vapourstat, low water cut off) is causing the cycling. Until you have identified the control, you really can't start to fix the problem.

danmayer175

So far, I can't tell which control is cycling the burner off. How do I check the thermostat? Unfortunately my gauge is the 1-30 type so I can't really tell what kind of pressure is in the boiler.

ChrisJ

If you carefully remove the trim cover from the thermostat you can watch the mercury switch. You'll know when it shuts off.

What model LWCO do you have? Does it say CycleGuard on it?

The way I see it you have many options but removing insulation is not one of them.

Relax, take pictures, share information and make changes slowly. Whatever you do don't start ripping stuff apart and making a ton of changes at once. The heating season has just started and you're on an awesome forum with many great people who can help.

Right now with the little you have said my first guess is you need more venting. Perhaps on both the mains and the radiators.

TheRooster

My experience with the insulation was that it did cause my pressuretrol to cut off the burner after I insulated the pipes.
That being said, my pressuretrol only cut off once the entire system was filled with steam and all main and rad vents closed and was recovering from a large setback.

If your radiators aren't heating then I would also think maybe its a venting problem but it is hard to know without a low pressure gauge or knowing if it is even the pressuretrol cutting off the burner. If it were a Cyclegard LWCO problem, the "off-time" would be way less than 8min unless a feeder had to add water.

SlamDunk

A follow up and correction to my short cycling problem. Maybe it will help you.

I found a steam trap failed closed in our largest radiator. It took five minutes for the radiator condensate to completely drain after I removed the defective trap. This, in conjuction with the radiator already valved off didnt help but it it didnt fix the short cycling either.

I had a self induced problem going on. And I think this is the root cause of my short cycling. I will know for sure tonight but while prepping boiler for heating season last month, I used a product called 8-way to scavenge O2. I believe I used too much because after I drained the boiler and refilled with plain water, the water stopped surging (that was my clue) as did the short cycling. All seems back to normal. It was late last night so I didnt have a long enough run to know for sure. I switched to forced air until tonight. When I applied the 8-way and tested boiler for an hour, there was no surging or short cycling.

ChrisJ

I'm 100% for using water treatment in steam boilers but you must use caution and less is more. In my opinion the reason many have problems with water treatment is either from dirty water or using too much treatment. Do you know what your PH was before adding and after adding the 8 way?

I'm curious how Rectorseal 8 way compares to Rectorseal Steamaster tablets which I use?

Please keep us informed.

SlamDunk

I suspect my pH was higher after using 8-way since I saw an occasional bubble slide down the sight glass. I do not have means to measure pH.

I used 8-way because liquid is either easy to get into boiler than a tablet. But like you said, more is less. However, I am inclined to think nothing is best.

ChrisJ

After running my boiler for a year with nothing and then switching to Steamaster for the past two years I'll never go back to plain water.

While monitoring PH and ensuring that my water is clean there are no negative effects, however, the amount of rust I get out of my boiler went from a lot to practically none.

Whether you're using treatment or not monitoring PH is an absolute must. I like to keep my PH around 9 but will always lean towards 10 rather than 8. Previously I was using a wide range paper that I think is something like 1 - 13 but it's too difficult to tell the colors apart. I'm switching to this : https://www.microessentiallab.com/ProductInfo/F01-WIDRG-060110-SRD.aspx

ChrisJ

After running my boiler for a year with nothing and then switching to Steamaster for the past two years I'll never go back to plain water.

While monitoring PH and ensuring that my water is clean there are no negative effects, however, the amount of rust I get out of my boiler went from a lot to practically none.

Whether you're using treatment or not monitoring PH is an absolute must. I like to keep my PH around 9 but will always lean towards 10 rather than 8. Previously I was using a wide range paper that I think is something like 1 - 13 but it's too difficult to tell the colors apart. I'm switching to this : https://www.microessentiallab.com/ProductInfo/F01-WIDRG-060110-SRD.aspx

BobC

i know the instructions for using steam master tablets is wildly wrong, the directions call for using 4 tablets as treatment when one tablet is usually more than enough. I use litmus paper to measure my PH. I had to drain about 2 gallons out of my Smith G8-3 boiler to get the PH down to 9 after i added ONE tablet.

I suspect your PH was too high and that causes surging.

Bob

KC_Jones

BobC said:

i know the instructions for using steam master tablets is wildly wrong, the directions call for using 4 tablets as treatment when one tablet is usually more than enough. I use litmus paper to measure my PH. I had to drain about 2 gallons out of my Smith G8-3 boiler to get the PH down to 9 after i added ONE tablet.

I suspect your PH was too high and that causes surging.

Bob

Though I didn't test my PH I added the tablets to mine and the performance of the whole system changed dramatically. I am pretty sure the PH was too high causing foaming. I got visual verification of the foaming I won't say how lets just say I did something a bit stupid. I skimmed again and diluted it dramatically now I have nice violet sight glass and a nice stable system. I can't comment on long term effects, but @ChrisJ is very particular about his system so I default to him on this topic. Just wanted to give my experience so far and reiterate you must be very careful how much is added. I am going to be testing my PH as soon as I decide between test strips and buying an actual meter (I like gadgets).

SlamDunk

My city sends me an annual water quality report. Just checked it online and the pH is consistently 8.5. I think I'm good.

"performance changed dramatically" is a good way to decribe what I saw. I could kick mself.

ChrisJ

SlamDunk said:

My city sends me an annual water quality report. Just checked it online and the pH is consistently 8.5. I think I'm good.

"performance changed dramatically" is a good way to decribe what I saw. I could kick mself.

Perhaps,
However mine tested mid 7s right out of the tap but after a few months in the boiler was low 6s.

I still urge you to test the PH from time to time.

ChrisJ

I'm confused,
Is danmayer175 and Slamdunk the same person?

SlamDunk

No. We apparently had a similar experience at the same time with the same conclusion and I hijacked his tread. Actually, he stopped posting.

SlamDunk

Follow up. Boiler is running like it used to. Nice and smooth. Insulation remains!

Fred

Good for you!

danmayer175

I'm back. I probably over-reacted to a few short cycles. Things seem to be OK now. The whole system seems to work better the higher the thermostat is set, and the colder it is outside. I'm adding venting for now (my Gorton #2 arrived today). At some point, I need to look at my water. My feedwater is right from our well, which has nothing more than a filter on it. I have a few bubbles in the sight glass, and some surging, especially during startup.

ChrisJ

Your water could naturally have a very high PH in which case you would need to use something to bring it down.

I don't know what is normally used in a boiler as I haven't had this problem but I have heard years ago they used vinegar.