Skimming, cleaner and temperature concerns

Gateacre · December 2024

Happy new year all. We've had a new 10 section Weil Mclain 80 series oil fired boiler installed and the skimming done by the installers was not as thorough as it ought to have been. We're priming and surging and foaming and dancing and occasionally tripping out in low water. I boiled a sample and it frothed like crazy. Getting the guys back is going to take time and I'd honestly rather do it myself.

I'm thinking of using TSP since I'm familiar with it and it's readily available here. Does anyone feel strongly about washing soda vs TSP? The installers used nothing but water.

2. We've got a new feed water tank controlled by the primary low water cutout, so I can't open the feed valve to adjust the water level. Where would you connect feed water? There's a garden hose style valve at the bottom beside the return. Forgive the terrible photo.

3. How much of a concern is thermal stress/shock during skimming, draining, filling and restarting from cold? Our previous boiler cracked and the suspicion is that cold water entering a hot boiler and excessive thermal cycling were to blame (building owner is 90 years old and will insist on setting back the thermostat as soon as his rads get warm. Combined with electric heaters in his office satisfying the thermostat, the old boiler would run as little as 2 hours a day. Long story. We've put an aquastat on the header to keep the boiler from going cold and a steam injector on the feed water tank to try and keep cold water away from hot castings. Am I concerned over nothing?

Any other tips or thoughts?

Thanks in advance

EBEBRATT-Ed · December 2024

You can skim with Tsp or washing soda. 1 lb does 50 gallons of boiler water so adjust accordingly. Bring the water up until it just starts to steam and shut the burner off. Add feedwater (use a hose on the drain valve if you have too with a washing machine hose and garden hose).

Just trickle the water in the slower the better. You want the water stream coming out to be no bigger than a pencil. The boiler will stay hot a long time. No need to worry about cracking.

I have only used TSP but I thnik it can cause environmental issues so maybe washing soda is better. Skim for an hour and a half or so. never had to do one twice. Then drain the boiler. Wait till the boiler cools down to refill. Drain and refill twice with just water. Then fill it and run it.

Gateacre · January 1

https://forum.heatinghelp.com/discussion/comment/1830976#Comment_1830976

Thanks so much Ed. You've been a great resource on a few questions I've had and I really appreciate it.

ethicalpaul · January 1

There are phosphate free TSP substitutes that should work well also.

Here is a link to one at HD

EzzyT · January 1

From looking at that picture I would be more concerned about the entire header of the boiler is welded. That will caused the boiler sections to start pulling apart because of lack of expansion on the header piping. The 1st few connections of supply risers should’ve been threaded connection.

Gateacre · January 12

https://forum.heatinghelp.com/discussion/comment/1831198#Comment_1831198

Yes. I questioned that too and looked it up in WM's installation manual for the 80 series boilers. They clearly indicate that the first 2 joints on each riser - from castings into each riser and the next joint in each riser just above the boiler jacket - must be threaded on the 6 through 9 section boilers. These models call for two 4" risers. Other joints in the NBP may be welded. However, the 10 and 12 section units with 3 risers don't have this requirement listed. I take your point and would have preferred to see the whole thing threaded but it ain't my money.

Skimming, cleaner and temperature concerns

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