LWCO: float vs. probe .. pros & cons?

jpf321

In my research for a new boiler .. I'm wondering what the pros & cons are for float vs. probe LWCO .. I understand that the first is the human factor of actually blowing down the float variety .. anything else that might help a decision in either direction. Thx. 

FJL

Well . . .

You could install both.  That is what my contractor did.

joe p_3

lwco

the lwco is a safety that shuts off the burner and can operate an auto fill... float requires regular blowdown; probes need to be pulled and cleaned with annual maint and tested by draining.  the type of autofill may actually be a bigger consideration.  look in to autofills that meter your water use and can be set with delays, also with readouts.  overfilling and filling too frequently can kill a boiler before its time.  safgard, honeywell, mcdonnel-miller.

BRIANJ

LWCO

Only suggestion I have is don't get the Probe type automatic Cycle Guard. Every 20 minutes or so it shuts down the system for a full mimute to check the water level. This interrupts the steam process. Steam condenses, loss of heat and if you have a long recovery cycle it will probably happen at least twice. Good Luck

jpf321

this is very good feedback

this is very good feedback and especially important since the Smith Series 8 units come with the CycleGuard "feature" .. I have been looking at the Smith 8 .. can anyone else expand on the CycleGuard feature? Here is the Smith 8 Manual .. cycleguard discussed on pg. 13 .. http://www.smithboiler.com/modules/lit_lib/download.asp?litFileID=929

MEK

CycleGuard OK?

I have a new boiler with a probe LWCO with CycleGuard. This thread seems to end without results on the effect of this on the heating cycles. I am interested in people's experience with them. Is the one-minute shut off too small to really affect the steam heating efficiency?

J Heritage

Cycle guard

Personally I think it will ruin the system efficiency and cause higher gas usage. I would also like to know if anyone has studied this further.

Hap_Hazzard

You don't suppose

that Hydrolevel would have studied this while they were developing the product. They had a full line of Safgard probe-type LWCOs before they developed the CycleGard. You don't think they would have spent all that money developing and marketing these if somebody could prove that it ruins the system efficiency and causes higher gas usage.



And then there are the boiler manufacturers that recommend them and even ship them with their boilers. Why would they do that if it made their systems less efficient? They spend a lot of money improving the efficiency of their products because it's a competitive industry. Wouldn't it be counterproductive to saddle them with a control that adds to the cost and lowers its performance? Why would they do that?



It's probably a big conspiracy. You should blow the lid off of this. Notify the media.

Patrick_North

Well now...

The purpose of the device is not to improve boiler efficiency, but to save it from  premature failure and to prevent boiler explosions. Compared to float type LXCO devices, it also creates a more hands-off situation for the user- something that appeals to lots and lots of people. It is certainly in the boiler manufactuer's interest to promote such a product (better reputation for longevity, easier to use, fewer warranty issues, etc.). And though the device certainly must affect the boiler's system efficiency, its efficiency rating woud not be changed. This is a good example of why AFUE ratings drive knowledgable people a little nutty.

"Conspiracy" may be a strong word here, but it seems to me that a) all the facts are not on the table, and b) the homeowner is the only one with anything to lose: fuel dollars. Remember too that boiler manufacturers "recommend" using only one boiler riser (in I&O manuals) when two is undoubtedly better from the perspective of the person paying the fuel bill. Could it be that they've done enough market research to know that requiring more than the bare minimum makes installation of their product more expensive- and therefore less attractive- to the non-steam expert homeowner?

 

In the end- to each their own. Lots of people love auto-feed water for a boiler- I tore mine out. I understood the upside, the downside, and made an informed choice. But with the CycleGaurd, the upside is clear, but the downside is unclear. What is the actual, factual effect of the CycleGaurd on efficiency? No idea. Their website doesn't seem to offer any ideas either, go figure. But I do know that the estimable Gerry Gill hates the darn thing. That's a pretty strong "undorsement" in my book. I'd love to know the facts, but the consumer is at a disadvantage in this regard. In such circumstances a bit of cynical speculation is to be expected- and is probably healthy.

Patrick

clammy

pros and cons

They  both have there ups and down ,depending upon the size of the boiler and cost of the job when the budget permits i usually use one of each can never be to safe in my opion .I personally really do not like the cyle guard with it's intermittmate shut down .To myself personally i feel it fit a niche for the boiler manafatures to reduce warranty boiler replaement due to the cut 2 pipe and tose in mentality of some installers and the the  fact that alot of these guys do not clean there systems or skim the boilers leaving alot of debrie and oil in the boiler and it's piping which we all know an cause surging and foam which can make both float and probe type lwco give a false level sensing causing premature failure .I have also found that in my opion that it does effect the system distrubition espically on larger systems where it takes up to 45 minutes just to get the steam to the end of the mains maybe not to much added time but it does add up and i personally feel that it does slightly effect the bottom line but not much .On larger system i use 2 operating lwco and 1 manually reset type ,same with pressure trolls or vaporstats it only makes sense when you invest 40 or 50 grand on a new boiler and on the commerial and industrally scene it is very common.Peace and good luck clammy

Steamhead

Probe-type, always

Probes have no moving parts so they will not fail nearly as often. If two LWCO units are needed, we use two probes if possible.

J Heritage

Cycle guard

Steamhead

Do you have a opinion on the Cycle Guard shutting the boiler early for safety VS system efficency.

Steamhead

Not my favorite

but if the manufacturer specs it, I wouldn't change it since it may affect the warranty.



Some boilers, like the MegaSteam, can be ordered with either the CycleGuard or the McDonnell & Miller probe-type LWCOs.

Ed2

Some data

I'm a homeowner with a CycleGuard on a Peerless 118000 BTU boiler feeding about 230 square feet EDR. The control is a vaporstat. There's a Wika 0-15 oz gauge. Every radiator in the house will heat about 1/3 of the way across at zero pressure, so I guess condensation is winning. In fact, i see slight vacuum much of the time that the radiators are heating across. In the end, it takes about an one half to one ounce to get all the way across all the radiators.



When the LWCO went into intermittent test, I started a timer when the test was over and the system re-enabled. It took 20 seconds for the damper to open and the system to fire. After another 20 seconds, we were back to 1 oz. So, within 40 seconds of re-enable and within 20 seconds of burning fuel, it was back to a useful pressure.



It's not very cold here now, so we'll see how it looks during winter, but right now I don't think the intermittent LWCO test is hurting the efficiency of the system. If you want them, I have times to reach pressures ounce by ounce up to 9 oz when the vaporstat shuts things down on pressure.



By the way, the system is still dirty. It's been skimmed 5 times and is much better, but it's not at its best yet. I don't think that affects this though (??).