Early heat exchanger failure

KevinPolly

I have had several customers with failures at 5 years on hot water boiler and there are no signs of excessive feed water ( no undiscoversd leaks) and the manufacture will not issue any warranty stating mineral deposits on interior of the heat exchanger these are CGa and CGI series boilers. Are there other installers with similar failures?

kcopp

What part of the country? What were the systems like? Non Barrier tubing? Air elimination?

KevinPolly

East coast, one old reverse return the other radiant with barrier tubing.

clammy

Have seen it on another line of boiler and as manafacture states those mineral despoits on the inside of the section is usually from excessive make up water .I would gather steam boilers ,if not you may have a leak on a under ground heat loop that has a slow leak ort some one is using the boilers drain valve as there personal hot water supply ( like washing cars once a week )..what area of the country are you in i know in north jersey we have hi chloride level and it does pre maturely eat steam boilers which are losing water due to bad air vents ,and leaky rad valves.You might be surprised how much make a boiler can take w just a few bad vents and a couple of leaky rad valves ,Had one last year that the HO caught close to 5 gallona a week .It adds up quickly.If your replacing them add a hydrolevel vxt recordable feeded great product and gives a gallon read out to keep track and make you aware that you got a leak ,Hope this help peace and good luck clammy

kcopp

So these were high mass/ water volume systems? So I gotta ask... what were you using for boiler protection from thermal shock?

KevinPolly

These were both hot water boilers, and cracks could be seen at the bottom of the heat exchanger and the locations are central jersey. I am aware of the effect of chlorides on the heat exchanger at the water line, this is not the case.

clammy

now that i,ve re read you post and there HW boilers .I would look to see if any loops where ran under the slab .I once had a service call where they had any issues with air re appearing in the system which can indicate a leak .I had a HO that unknowingly would use the bottom boiler drain for washing there cars what a nightmare .Went there like every 2 weeks for air in system and it was a older system drove us crazy finally one day i pull up and long behold they got a garden hose hooked up to the boiler washing cars .Would have never fiqured that one out .But a big clue was bright orange water that would come out when i went to purge the boiler out .I have also witenessed this with under ground loops .Personally i would do a system pressure test to make sure she s water tight also don t leave feed valve open and make sure they have a low water cut off and or a pressure switch to ebnsure there water in boiler .Peace and good luck clammy

KevinPolly

Yes the reverse return system is mixing supply and return water to prevent thermal shock, and the radiant system is primary secondary.

clammy

yeap those boiler don t hold much water volume may have been better to ps pipe them and put a danfgoss esbe thermic valve on the return to keep those water temp up and prevent flue gas condensation .Seems some small low water content boilers don t like those low temps durning a cold start .It sucks but on a boiler replacem,ent take a look at thoose esbe thermic valves or pipe in a system by pass off of your main system pump ,just do a little math to fiqure out what size to use it usually either 1/2 or 3/4 on most small to mid sized residental homes .I learned this trick from a smart german ,a small bypass help bring your return temp up as the boiler warms ,i bypass on the pump outlet and use a globe valve to adjust flow of course pump on supply and usually a small spring chk in the by pass w union for ease of replacement or repair.Works great on oil boiler with triple aquastat and low limit on circ ,helps those retrun temps and cuts down on the circ cycling on low limit good little trick to put in the bag .Remenber to leave a note if you do installa bypass alot of guys have no idea and close them ,i usually mark the valve stem and remove the handle and tag the valve so one one completly closes it .Again hope this helps peace and good luck clammy

Gordy

Hatterasguy said:

clammy said:

.I learned this trick from a smart german ,a small bypass help bring your return temp up as the boiler warms ,i bypass on the pump outlet and use a globe valve to adjust flow of course pump on supply and usually a small spring chk in the by pass w union for ease of replacement or repair.Works great on oil boiler with triple aquastat and low limit on circ ,helps those retrun temps and cuts down on the circ cycling on low limit good little trick to put in the bag .Remenber to leave a note if you do installa bypass alot of guys have no idea and close them ,i usually mark the valve stem and remove the handle and tag the valve so one one completly closes it .Again hope this helps peace and good luck clammy

Sorry for the hijack but I have a burning question on those bypasses..............

If you have two zones and both circulators are on the supply, where do you connect the bypass? If you connect it on the 1 1/4 manifold BEFORE the circulators, you cannot get flow from the supply to the return as the pressure on the return side will be higher.

Burnham shows the bypass on the 1 1/4" manifold, before the circs, and I do not believe it can possibly work the way they have depicted it in the manual.

I see what your saying. The bypass pipe would have to be down stream of the system circ. The diagram is for tempering supply temps it would seem to me. All though its deffinetly not explained as its function.

Gordy

Yes I agree.

hot_rod

The ONLY way to provide positive boiler return protection is with a temperature sensing function and a valve or a pump that responds to that temperature.

A bypass pipe with a manual balance valve cannot and will not provide adequate protection, under all conditions.

A pump, even a delta T pump in a bypass loop, cannot and will not provide adequate protection.

Connecting todays low mass, low water content cast boilers to any type of system radiant, cast rads, etc that are high mass, or large water content needs to be done carefully.

3 way thermostatic are simple, inexpensive devices that can accomplish 100% return temperature protection. along with a handful of tekmar boiler and mixing controls.

Remembering the Weil GV series, a simple fixed temperature Hoffmann thermostatic mixer worked extremely well in that cast boiler.

Burnham Revolutions did it with a variable speed bypass pump that monitored and responded to return temperature.

Early Viessmann cast boilers, simpler yet, connect the pump to an aquastat set to 140F. As long as the boiler can run with zero flow, that is as simple as it gets.

hot_rod

What's wrong with two zone valves? As long as the circs has the fizz to handle the job ZV work great, less power consumption, 100% shutoff, no check valves required.

Better yet a couple PICCVs

Gordy

Funny how some CI boilers can sop up cold return water with a simple bypass like a billy goat drinking antfreeze belching and living another day..

clammy

to answer your question installing a by pass with more then 1 circ .I m talking about a system by pass which is piped off the supply on the pump discharge and ties into the return for that loop or zone .A simple spring chk and a globe is installed in this line usually with a ball valve and union for ease of replacement of spring chk,.I know this is not the greatsest but when your boss is cheap and you get tried of cleaning the same soaked oil fired boiler because of prolonged low temp you pipe in a by pass .It simple and it does work .In cases with multi zones there s usually the original hi volume zone and then a bunch of mirco base board zones,It s a tool that i use here and there when you just can t talk them into a thermic valve some people and contractors just won t listen so you this and it s better then nothing and it s worked for me in a pinch . good and luck clammy

clammy

When i have used this method it was usually to help boiler stay above flue gas condensate temp and in most cases not ever zone needed a by pass it would usually be the large mass zone.I have also seen and used the low limiton the circ method but that seems to cycling the pump to much and put the boiler under temp swings and pump cycling ,the by pass method works a little better and does bring the return temp up depending on weather you did some math to proper size that by pass.I had gotten this set up idea from when i was in germany over 20 years ago .They like to keep there kettles warm and well above flue gas condensation temp ,kettle warm and re set the system temp then no flue gas issues ,thermal shock non of it .Peace and good luck clammy

clammy

Also have seen it and done it with a simple zone valve and aquastat on some 3 boiler systems tied into a extreme gravity system it worked great .Used 3 small 007 and they had a hi vee series 60 on the return on the existing system .No tekmar stage control either just 2 aquastat to bring them on and when she got to 160 1 boiler would drop our .Work for some cheapos who would not pay for a stage controller there lose.There s alkways more then one way to skin a cat peace and good luck clammy

jonny88

Was waiting for you to get involved Hatterasguy and you still have me scratching my head.When I open gate valve on return thermometer on heel tee on return of boiler goes up as I raise it.I am using circs on this system pumping away.This ES2 is running on ODR and we were concerned about condensation in chimney as boiler is able to handle low temp.If I am wasting time I will be only more than happy to eliminate bypass.
Thanks in advance.