High pressure blowdown

StevenNYC

With the all the valves shut off in the following near boiler piping pictured below, would I be a be able to perform a high pressure blowdown and test the high pressure cutout or would I need another gate valve on the equalizer pipe? My intuition tells me that I need one more valve installed on the equalizer itself to keep steam from creating chaos within the boiler. Any recommendation on what is a safe pressure to perform a good bottom blowdown?

KC_Jones

No additional valves required.  Close them and let ‘er rip.

If you do the blowdown, it’s a bit violent, but the pressure dissipates fairly quick.  I wait for mine to cut out on pressure then turn it off prior to opening the drain.

StevenNYC

@KC_Jones

KC_Jones said:

No additional valves required.  Close them and let ‘er rip.

If you do the blowdown, it’s a bit violent, but the pressure dissipates fairly quick.  I wait for mine to cut out on pressure then turn it off prior to opening the drain.

What pressure is your cutout set too?

HVACNUT

I hope that electric is temporary. Why was the sheathing removed?

KC_Jones

StevenNYC said:

@KC_Jones

KC_Jones said:

No additional valves required.  Close them and let ‘er rip.

If you do the blowdown, it’s a bit violent, but the pressure dissipates fairly quick.  I wait for mine to cut out on pressure then turn it off prior to opening the drain.

What pressure is your cutout set too?

For blowdowns it's set to 9 psi

Jamie Hall

If you are proposing to do a high pressure -- anything over 3 psi -- blowdown, be sure that all sensitive controls are valved off from the boiler or removed. That would be vapourstats, float type low water cutoffs (unless they are rated for high pressure), low pressure gauges, etc. etc.

And be very very careful. As @StevenNYC noted, it can be quite violent. Stand well clear of the blow down valve when it is opened and be prepared to turn the burner off immediately.

KC_Jones

Jamie Hall said:

If you are proposing to do a high pressure -- anything over 3 psi -- blowdown, be sure that all sensitive controls are valved off from the boiler or removed. That would be vapourstats, float type low water cutoffs (unless they are rated for high pressure), low pressure gauges, etc. etc.

And be very very careful. As @StevenNYC noted, it can be quite violent. Stand well clear of the blow down valve when it is opened and be prepared to turn the burner off immediately.

I have an old washing machine hose that I put into a 5 gallon bucket. It's violent at first, but the vessel is relatively small so the pressure bleeds down fairly quick.

To the OP, I can't tell what valves you have, but I wouldn't do it unless the valve I was using what a 1/4 turn ball valve of some kind. You want to be able to close it fast "just in case". My valve is actually where you have a cap below the Hartford loop connection.

I run water treatment and have only done the blowdown twice in 7 years and even then I didn't have much crud. The water treatment keeps things fairly clean.

Daveinscranton

I come from a different line of work.  Spent a lot of time doing it too.  If I can, I would suggest some care and caution.  Especially if your boiler water has a high pH.  The surface of the eye can get a chemical burn quickly from high pH (base).  Gives a liquifactive necrosis.  Fancy way of saying that the cornea liquifies and dies. Brief exposure sometimes can be helped by drizzling in normal saline solution over hours.  Cornea replacement if not.  Curiously, the eye tolerates acid better than base.  ( I wouldn’t try that one out either)

I have a friend who was blowing hydrides (worse than boiler water with a high pH) out of his dryer for his gas well.  Extreme base at high pressure.   Has a defect in his cornea to this day.  

I recognize that folks have been doing this safely for decades.  Or many decades.  Worth mentioning perhaps.  Not intended to be alarmist.

best wishes 

cross_skier

Would be interesting to see a video of the blowdown

StevenNYC

@HVACNUT

HVACNUT said:

I hope that electric is temporary. Why was the sheathing removed?

Lol yes it’s temporary. Needed heat for the winter during renovations.

StevenNYC

@cross_skier

cross_skier said:

Would be interesting to see a video of the blowdown

I’ve been looking everywhere. Can’t find one anywhere.

Hap_Hazzard

Aren't you going to blow it down through the return pipe? I highly recommend it. If so you'll need a ball valve on the return, and it's always good to put an elbow on it to deflect the water into a big bucket instead of shooting it across the basement.

StevenNYC

@Hap_Hazzard

Hap_Hazzard said:

Aren't you going to blow it down through the return pipe? I highly recommend it. If so you'll need a ball valve on the return, and it's always good to put an elbow on it to deflect the water into a big bucket instead of shooting it across the basement.

Wouldn’t I need a shutoff valve in the equalizer pipe in order to blow down the boiler in the location you’re referring to? Otherwise I’ll just be getting a mix of high pressure steam and water there no? I was planning on blowing it down from the other side of the boiler where the boiler drain is at the bottom.

Hap_Hazzard

StevenNYC said:

Wouldn’t I need a shutoff valve in the equalizer pipe in order to blow down the boiler in the location you’re referring to? Otherwise I’ll just be getting a mix of high pressure steam and water there no? I was planning on blowing it down from the other side of the boiler where the boiler drain is at the bottom.

No. It's below the water line. In fact, it's the lowest tapping on the boiler, and it runs through all the sections. The drain cock tapping only drains the end section directly, and it's much smaller and usually has a globe valve on it, unless you've replaced it. A full port ball valve on your return is the way to go.

By the way, you will see a lot of steam when you do a blow-down under pressure, because pressure raises the boiling point a little, and some of the superheated water that's being forced out is going to flash to steam, so be careful. It's not as bad as opening a radiator cap on a hot engine, but you should expect a little violence.

StevenNYC

@Hap_Hazzard

Hap_Hazzard said:

StevenNYC said:

Wouldn’t I need a shutoff valve in the equalizer pipe in order to blow down the boiler in the location you’re referring to? Otherwise I’ll just be getting a mix of high pressure steam and water there no? I was planning on blowing it down from the other side of the boiler where the boiler drain is at the bottom.

No. It's below the water line. In fact, it's the lowest tapping on the boiler, and it runs through all the sections. The drain cock tapping only drains the end section directly, and it's much smaller and usually has a globe valve on it, unless you've replaced it. A full port ball valve on your return is the way to go.

By the way, you will see a lot of steam when you do a blow-down under pressure, because pressure raises the boiling point a little, and some of the superheated water that's being forced out is going to flash to steam, so be careful. It's not as bad as opening a radiator cap on a hot engine, but you should expect a little violence.

Thanks for the insight. This makes a lot more sense. I just looked up boiling temp at 9 psi above ambient. It’s close to 250 degrees Fahrenheit. Yowzer lol…

Jamie Hall

StevenNYC said:

@Hap_Hazzard

Hap_Hazzard said:

StevenNYC said:

Wouldn’t I need a shutoff valve in the equalizer pipe in order to blow down the boiler in the location you’re referring to? Otherwise I’ll just be getting a mix of high pressure steam and water there no? I was planning on blowing it down from the other side of the boiler where the boiler drain is at the bottom.

No. It's below the water line. In fact, it's the lowest tapping on the boiler, and it runs through all the sections. The drain cock tapping only drains the end section directly, and it's much smaller and usually has a globe valve on it, unless you've replaced it. A full port ball valve on your return is the way to go.

By the way, you will see a lot of steam when you do a blow-down under pressure, because pressure raises the boiling point a little, and some of the superheated water that's being forced out is going to flash to steam, so be careful. It's not as bad as opening a radiator cap on a hot engine, but you should expect a little violence.

Thanks for the insight. This makes a lot more sense. I just looked up boiling temp at 9 psi above ambient. It’s close to 250 degrees Fahrenheit. Yowzer lol…

What's not immediately obvious about blowing down at high pressure -- the entire contents of the oiler are at that high temperature, and if you remove the pressure, such as by opening a blowdown valve, the entire contents are going to try to boil. And will, unless you get the valve closed pronto. Be sure that if you try to blow down at high pressure the valve will close and you will be able to reach the valve to close it.

delcrossv

Maybe a hose barb and a length of large diameter hose on the end of the valve would be helpful?

Hap_Hazzard

Maybe if you use that heavy-duty discharge hose that looks like a fire hose.

ChrisJ

Hap_Hazzard said:

Maybe if you use that heavy-duty discharge hose that looks like a fire hose.

We are talking about 10 psig here right?

Jamie Hall

It isn't the pressure so much -- it's that a good bit of the water in the boiler will boil, and will force a lot of very hot water out somewhere. Very interesting.

ChrisJ

Jamie Hall said:

It isn't the pressure so much -- it's that a good bit of the water in the boiler will boil, and will force a lot of very hot water out somewhere. Very interesting.

I'm sorry, reading through the comments I thought someone was talking about blowing down the UP Big Boy at full pressure 


The water will maintain the 10 psig.  

It's very hot water and you need to be careful. 

delcrossv

At 10 psi radiator hose would work fine. send it right into the floor drain (cap removed). No muss, no fuss.

A lot safer than a spigot into a bucket 😳

ratio

delcrossv said:

At 10 psi radiator hose would work fine. send it right into the floor drain (cap removed). No muss, no fuss.

A lot safer than a spigot into a bucket 😳

I think I'd set a cinder block (or more?) on the hose & drain, to keep the end where it belongs.

StevenNYC

@Hap_Hazzard

Jamie Hall said:

StevenNYC said:

@Hap_Hazzard

Hap_Hazzard said:

StevenNYC said:

Wouldn’t I need a shutoff valve in the equalizer pipe in order to blow down the boiler in the location you’re referring to? Otherwise I’ll just be getting a mix of high pressure steam and water there no? I was planning on blowing it down from the other side of the boiler where the boiler drain is at the bottom.

No. It's below the water line. In fact, it's the lowest tapping on the boiler, and it runs through all the sections. The drain cock tapping only drains the end section directly, and it's much smaller and usually has a globe valve on it, unless you've replaced it. A full port ball valve on your return is the way to go.

By the way, you will see a lot of steam when you do a blow-down under pressure, because pressure raises the boiling point a little, and some of the superheated water that's being forced out is going to flash to steam, so be careful. It's not as bad as opening a radiator cap on a hot engine, but you should expect a little violence.

Thanks for the insight. This makes a lot more sense. I just looked up boiling temp at 9 psi above ambient. It’s close to 250 degrees Fahrenheit. Yowzer lol…

What's not immediately obvious about blowing down at high pressure -- the entire contents of the oiler are at that high temperature, and if you remove the pressure, such as by opening a blowdown valve, the entire contents are going to try to boil. And will, unless you get the valve closed pronto. Be sure that if you try to blow down at high pressure the valve will close and you will be able to reach the valve to close it.

After reading all these comments, I think I’m just gonna leave it alone 😳
You guys are scaring the crap out I’d me 😖

reggi

StevenNYC said:

@Hap_Hazzard

@Hap_Hazzard

Wouldn’t I need a shutoff valve in the equalizer pipe in order to blow down the boiler in the location you’re referring to? Otherwise I’ll just be getting a mix of high pressure steam and water there no? I was planning on blowing it down from the other side of the boiler where the boiler drain is at the bottom.

No. It's below the water line. In fact, it's the lowest tapping on the boiler, and it runs through all the sections. The drain cock tapping only drains the end section directly, and it's much smaller and usually has a globe valve on it, unless you've replaced it. A full port ball valve on your return is the way to go. By the way, you will see a lot of steam when you do a blow-down under pressure, because pressure raises the boiling point a little, and some of the superheated water that's being forced out is going to flash to steam, so be careful. It's not as bad as opening a radiator cap on a hot engine, but you should expect a little violence.

Thanks for the insight. This makes a lot more sense. I just looked up boiling temp at 9 psi above ambient. It’s close to 250 degrees Fahrenheit. Yowzer lol…

What's not immediately obvious about blowing down at high pressure -- the entire contents of the oiler are at that high temperature, and if you remove the pressure, such as by opening a blowdown valve, the entire contents are going to try to boil. And will, unless you get the valve closed pronto. Be sure that if you try to blow down at high pressure the valve will close and you will be able to reach the valve to close it.

After reading all these comments, I think I’m just gonna leave it alone 😳 You guys are scaring the crap out I’d me 😖

I think you were very smart to inquire before just letting her rip... you probably had a feeling in your gut..if I may suggest...start off at a very low pressure to get your feet wet ( not literally ) and work yourself up as you get a feel for the action ?
Maybe let someone else concur before ( if ) you decide to attempt and heed all the warnings and suggestions by those that have your safety concerns first..G/L with whatever you decide to..or not to do

StevenNYC

reggi said:

StevenNYC said:

@Hap_Hazzard

Jamie Hall said:

StevenNYC said:

@Hap_Hazzard

Hap_Hazzard said:

StevenNYC said:

Wouldn’t I need a shutoff valve in the equalizer pipe in order to blow down the boiler in the location you’re referring to? Otherwise I’ll just be getting a mix of high pressure steam and water there no? I was planning on blowing it down from the other side of the boiler where the boiler drain is at the bottom.

No. It's below the water line. In fact, it's the lowest tapping on the boiler, and it runs through all the sections. The drain cock tapping only drains the end section directly, and it's much smaller and usually has a globe valve on it, unless you've replaced it. A full port ball valve on your return is the way to go.

By the way, you will see a lot of steam when you do a blow-down under pressure, because pressure raises the boiling point a little, and some of the superheated water that's being forced out is going to flash to steam, so be careful. It's not as bad as opening a radiator cap on a hot engine, but you should expect a little violence.

Thanks for the insight. This makes a lot more sense. I just looked up boiling temp at 9 psi above ambient. It’s close to 250 degrees Fahrenheit. Yowzer lol…

What's not immediately obvious about blowing down at high pressure -- the entire contents of the oiler are at that high temperature, and if you remove the pressure, such as by opening a blowdown valve, the entire contents are going to try to boil. And will, unless you get the valve closed pronto. Be sure that if you try to blow down at high pressure the valve will close and you will be able to reach the valve to close it.

After reading all these comments, I think I’m just gonna leave it alone 😳
You guys are scaring the crap out I’d me 😖

I think you were very smart to inquire before just letting her rip... you probably had a feeling in your gut..if I may suggest...start off at a very low pressure to get your feet wet ( not literally ) and work yourself up as you get a feel for the action ?
Maybe let someone else concur before ( if ) you decide to attempt and heed all the warnings and suggestions by those that have your safety concerns first..G/L with whatever you decide to..or not to do

@reggi this forum has been a great resource. A lot of people gave up on steam but my fuel bills have been cut in half and I’m running at a balmy 73 degrees lol. Still have a little bit of tweaking to do with balancing and a couple of pesky noisy vents but other than that I have really been enjoying nice quiet toasty heat at half the cost.
Steam boilers like everything else just need a little tlc and some basic knowledge.

cross_skier

If you do start with low pressure consider creating a video for feedback and to educate.

ChrisJ

I'm waiting for @KC_Jones to make a video at 10 PSIG.

Hap_Hazzard

ChrisJ said:

We are talking about 10 psig here right?

No, I'm assuming the hose would be open. You'd only build 10 psi if you clamped the hose shut. You'd have to be careful to get all the kinks out before opening the valve, but I don't see why a 2" rubberized canvas discharge hose couldn't handle that flow.

Hap_Hazzard

BTW, this is where I do blowdowns. I've never done it at pressures higher than the Pressuretrol's cut-out point (1.5 psi), but there's still a lot of steam.

Jamie Hall

Hap_Hazzard said:

ChrisJ said:

We are talking about 10 psig here right?

No, I'm assuming the hose would be open. You'd only build 10 psi if you clamped the hose shut. You'd have to be careful to get all the kinks out before opening the valve, but I don't see why a 2" rubberized canvas discharge hose couldn't handle that flow.

Um... well, sort of. In order to build to 10 psig, the hose has to be shut. Then what will happen when the clamp is loosed is that the water in the boiler will boil and force water out with some vigour, and keep boiling until either the water is gone or the water in the boiler and the boiler itself has been cooled enough by the boiling to stop.

The hose, meantime, will flail about quite enthusiastically, drenching everything in sight with boiling water, unless you restrain it.

StevenNYC

Hap_Hazzard said:

BTW, this is where I do blowdowns. I've never done it at pressures higher than the Pressuretrol's cut-out point (1.5 psi), but there's still a lot of steam.

@Hap_Hazzard what’s the black 1” pipe connected to?

delcrossv

The hose is never clamped. Attach a hose barb to the ball valve (screwed fitting), put the hose on the barb with hose clamps, place the hose, open the valve and go to town.

@Jamie Hall is right, you'll want to weight it down.

Hap_Hazzard

StevenNYC said:

@Hap_Hazzard what’s the black 1” pipe connected to?

The wet return. I can close the Hartford loop and drain and flush the wet return without letting any water out of the boiler.