Doing a blowdown under pressure.

ChrisJ

Before firing the system up again for the fall I really want to do a blowdown.  The last time I did this I closed both of my king valves and the return valve and then adjusted my pressuretrol for 3psi or so.



This time I want to go to a higher pressure, but not sure how high is recommended?  I'm assuming 10PSI or under should be perfectly safe?



Also,  I don't want to mess with my pressuretrol setting if possible.  Is it safe to just hold the mercury bulb from tripping with my finger and let go when I hit the desired pressure?   My concern is I don't know if this may damage the diaphragm in the pressuretrol.

Hap_Hazzard

How high were you planning to go?

Check your manual, but I think the max operating pressure is around 20 psi, and the surge pressure is around 50. I think your safety valve will pop before you can damage the pressuretrol. You wouldn't want that to happen.

ChrisJ

safety valve

I believe the T&P will pop at 15PSI so I don't want to get close to that but I'm wondering how high most guys go?  5? 8? 10? 12?



I guess one of my concerns is I noticed last time I did this at 3PSI the pressure crept up a little bit past where I shut the burner off so my fear is if I get too close to 15PSI I might be very sorry, or maybe its good to test it?  Something tells me its a bad bad thing when that pops.

Hap_Hazzard

Very bad

unless you're into scalding. Dan has a description of what it's like on here somewhere. It didn't sound fun.



Anyway, I'm curious about how much pressure to use too. Part of my new header design was to allow for blowing down the boiler. There is a short video on the subject somewhere in the resources. I'll see if I can find it when I get home tonight.

JStar

Pressuretrol

You can jump out the electrical contacts on the Pressutrol to make it easier.

Hap_Hazzard

That's what I was thinking.

When I skimmed it last year I just jumped the terminals in the lwco for the pressuretrol and the thermostat with a pair of clip leads.

ChrisJ

shorting / jumping pressuretrol

I thought about that too, except its just as easy to simply and a lot safer hold my finger on the mercury bulb.

gerry gill

why dont you just

open a return plug on the side of the boiler and go in with a homemade 'wand' hooked to a garden hose and wash out the boiler. I did it for a customer today. You'll be amazed at what comes out.

ChrisJ

hosing it down

Should I make up a custom head for my pressure washer using soft copper tubing?



I'm assuming the easiest way to hose a boiler down like my EG-45 would be through the skimmer?

Rod

Flushing the Boiler

Hi Chris-

  I don't know about using a pressure washer. That might be overkill!   It works quite well just using a garden hose. I believe your safety is on top of the boiler and that might be the best place to flush from. Also you can use your skim port.

I hook one hose to the bottom boiler drain valve and lead it to a floor drain and then just run a lot of water through the boiler using another garden hose and a wand I made up with fittings from Home Depot.  The water splashing around the inside cleans off most of the sediment.

- Rod

gerry gill

i have a copper pipe

with a ball valve that has a female hose connection on it and the working end is a 90 degree elbow with the leg cut off so that the water still goes sideways but is essentially a straight pipe. I just roll it in circles inside the boiler.

Hap_Hazzard

Video

Here's the video on near-boiler piping that mentions blowing the boiler down under pressure. He says 10 lbs. That'd make me a little nervous.



http://www.heatinghelp.com/article/107/Steam-Heating/118/Steam-boiler-near-boiler-piping