hmmmm... I hope you didn't do an 'ooops'...

When you say 'cushion tank' I'm pretty sure you are talking about the expansion tank.

If that tank is the type that looks like a propane tank from a gas grill, you should NOT have 'drained' it... if you let the air charge out, it can no longer function as it needs to...

Is this the type of tank you have?

Or, is it a large steel tank strapped to the ceiling above the boiler?

 

Did I miss somewhere that there is a drainable (non bladder) tank on this system?

 

Grady, I don't think so... we hadn't got to that part yet... I was hoping that we wouldn't need to...

 

large steel one strapped to celing
I am sure it is expansion tank same as on my own boiler

 

soory meant to say expansion tank.looks home made.or welded together on steel plant when it was operating here.
Lot of people use to make them when they shifted over from coal fired forced air.

 

OK then...

When you drained it, are you certain that you got ALL the water out and it was COMPLETELY empty?

What happens usually is that when you drain them, they get a 'suction lock' inside... the water will stop draining, but the tank won't be empty. It's like when you put your finger on the end of a drinking straw and lift it out of the glass... the liquid stays in the straw... if you didn't get ALL the water out, it could be the reason that the pressure is going to 30 now...

Shut the boiler off, and:

There should be a valve on the line from the boiler to the tank, and you need to close that valve. Hook up the hose to drain the tank and when the water stops flowing, loosen the hose and let it suck some air back in to break the suction... the water should start draining again... what ever you need to do to get that tank empty.

When you are sure it's empty, close the drain, and open the shutoff valve in the line SLOWLY... water will go back into the tank... it will fill the tank about 1/2 to 2/3 full, that's normal... as long as the air bubble in the tank is big enough to handle the expansion...

 

I did that excatly as you just said.shut down furance turned off valve drained with hose losend hosed and tightend till I was pretty sure all water was gone Turned on water supply .Started up furance worked fine .presure would not go above 14 plounds till I ajusted feed valve turned it about half turn pressure


came up.Now pressure goes up to 29 psi.when hot( lots of heat in third floor rads)That seem a little high.backing valve off does not seem to help..I think you were right the first time it was that damm feed valve.full of crut inside
cape tish

 

Dodged a bullet on the tank.

In order to reduce the pressure, in addition to changing the setting on the valve you will have to drain some water. Back off the valve about 1/4 turn & open a valve, other than the tank valve to get the pressure down some. You may end up replacing the reducing valve but let's not go there unless we have to.

Agreed, Trooper?

 

hey guys That was supposed to be 23c heat on third floor not f be kind of cold.
Just got to many things on my mind.I will check out that valve like you suggested drain some water and back off a little.My grandson said it was working fine not kicking off.Just do not want to leave pressure that high.Thanks guys

Talk later

Have a great day

capetish

 

Hi Grady and Trooper

Never got chance to try ajusting that feed valve seems to be working .Pressure little hi.It is not kicking off though Running at 28-30psi.I will try ajusting the weekend.Thank you guys for your expert help We all have a chance to learn lot from people like you..
Have a great night .will keep in touch

Capetish

 

Hi
Got up to ajust that feed valve today.
Pressure is 18psi when cool 24-25lbs when boiler is hot.Set lock nut with screwdriver and spanner. Ran for half hour seems fine .Just called my Grandson he said it still has same readings
That seems ok ,do you Think?
Should water valve feed from house to reg be turned off after proper boiler pressure is obtained
Valve was open when I started.

Thanks

Capetish

 

That sounds fine to me. Let it run and just keep an eye on the pressure. I would leave the manual feed valve open.

So how many points did you score?

 

NJ Trooper and Grady and others - thanks for all this info. I just bought my first place and had to deal my baseboard hot water heater. This thread was great for figuring out how this system works and making sense of all the components. I bought a condo specifically so I don't have to deal with all the "home maintenance" stuff, but couldn't avoid this one. So again, thanks. This thread made a lot more sense than the Laars manufacuter manual.

I had poor heating performance and an antire segment of my livingroom with cold radiators (this zone was split into two branches). After reading this thread I decided it must be this "air lock" situation so I throw some electronic valves to manual, played around with the various vavles to isolate one branch at a time and flushed each one for a couple of minute with the feed vavle open - seems to have done the trick. I've searched high and low and I'm pretty sure there's not a single air bleeder vavle anywhere on my system.

In case someone is still monitoring this thread I'd like to throw in another question: Why does pressure in the system matter and why is a certain psi required to get water up to higher floors? If it's a closed loop then isn't the pressure "pressing" in both direction equally?

Thanks,
Oleg

 

Hi Oleg! Welcome to the forums, and glad we could help you!

It's all in the physics. Let's say that you had a vertical pipe, open at the top, closed with a pressure gauge at the bottom. Let's also say that pipe is 20' tall. The diameter of the pipe itself makes no difference.

For every foot of water that you pour into that pipe, you will register 0.432 PSI on the gauge. Thus, if you filled it to the 10' level, you would read 4.32 PSI, 20' you would see 8.64 PSI.

I said the diameter of the pipe doesn't matter... and it doesn't. If you went into a swimming pool and swam down to 20', there would be 8.64 PSI exerted on your body.

That's the physics...

So, in a CLOSED system, in order to ensure that you had adequate pressure at the TOP of the system in order to keep the air in the water DISSOLVED in the water, you would have to have AT LEAST 0.432 PSI per foot of system height. We always add 3-4 PSI on top of that pressure as a 'guarantee' ... for 'headroom'...

Also, in some cases, if the water is quite hot, as the hot water travels up to lower pressure, it is possible for that very hot water to flash to steam... and you DON'T want that!

There are some other reasons for the 'extra' pressure, but won't get into that just now...

So, that STATIC pressure in the system is required in order that the ENTIRE system always remain filled with water, and that there is always a few PSI of pressure at the very top.

The CIRCULATING PUMP does not do the work of 'pushing' this water to the top. It is not that powerful. All the pump does is add energy to the water and MOVE IT AROUND the closed loop. Very much like a FERRIS WHEEL. And, as you correctly said,

Yes, more or less... once the wheel is turning, gravity is pulling down as much as the pump is pushing... once the wheel is turning, the only energy that the pump must put into the water is that which is required to overcome the FRICTION of the piping network.

Вы понимаете ?

 

That makes perfect sense. I forgot about that whole air dissolved in water thing - I don't drink much soda

PS - What are those funny characters at the bottom of your post? Just kidding, I understand! (Even corrected to by properly conjugated now!)

-Oleg

 

Олег, I'm glad you 'got it'! I know I may have guessed the nationality incorrectly... I'm sorry if I did, but glad you did understand!

Feel free to ask as many questions as you like! I'm not afraid to type!

 

No sweat, you guessed it right (Belarus). I just haven't read Russian in a looong time. Where's your knowledge of the language come from? Or are you just really good with google translate?

Well if you insist on more questions -

Last night i was ready to declare victory zone 1 (downstairs), after flushing the air out, now heated jsut fine. I added zone 2 (upstairs bedrooms) by overriding the program on that thermostat and all seemed well.

Over night only zone 2 was on and there was good heat and not much noise. Just some pings in the radiators which I assume are jsut thermal expansion? They sound very similar to my bike when I just turn it off and the exhaust pipes and all else cools. Doesn't bother me too much, but is there much I can do about this?

In the morning is when the real problem started. At this point zone 2 turns off and zone 1 turns on and runs alone. Now, whenever the boiler fires, there is a loud steady vibration in the pipes. It sounds like a humming noise like a loud florescen light ballast or a leaf blower going outside. The sound only happens when the boiler is firing and stops as soon as the flames go out. So I assume this is no longer an air issue since the pump is still running and moving water around when the boiler is between firing cycles? Any idea what could be causing it?

The boiler is a Laars Mini-Therm. I believe this is the manual for it: http://www.laars.com/LinkClick.aspx?...=1607&mid=4009

I can't figure out what component in it could be causign this humming - if that's where it's comign from. It was louder in the boiler closet and I could definitely feel the pipes buzzing. Any ideas?

Last night when I was flushing the system I wasn't sure what to do with the bypass valve. I left it fully closed. After reading that manual I jsut picked up an infrared thermometer at Sears to make sure I'm within the specific <30f inlet-outlet temperature drop. Could this have anything to do with it?

Any ideas appreciated?

Thanks,
Oleg

 

The by-pass could be the source of the noise. Try opening it 1/2 way to see if it helps. If little to no improvement try opening the by-pass all the way. From what I remember, those Mini-Therms are tempermental little beasts.

 

My 'day job' puts me in close contact with many nationalities, and learning some of their language has always been a 'hobby' of mine. And yes, Google Translate helps me a LOT! One of my better friends is from Moldova, and I have learned MANY things from him that I can not repeat here!

There often isn't much that can be done for the 'pinging', but some things are worth experimenting with.

There are a few things I usually suggest... inspect all the baseboard elements (when you say 'radiators' I assume you mean fin-tube baseboard?) and look to see if there are plastic 'shims' between the elements and the holding brackets. While you have the covers off to do so, brush and vacuum out all the little dust devils that have hidden in there over the years. More air flow around the elements sometimes helps.

If you find that some or all of the shims are missing, you can try cutting pieces of plastic milk cartons and place them between so that the element can 'slide' as it is expanding and contracting.

Often the addition of an 'Outdoor Reset Module' will help, because it will modulate the temperature of the water based on the outdoor temp. In the 'shoulder seasons' when the water doesn't NEED to be as hot to heat the home, it will allow cooler water to circulate. Cooler water will produce less expansion, AND might save you some fuel too! These modules can be pricey... weigh against 'payback time'...

Yes, see below... and also note that this information may also help the 'pinging' of the radiators...

Yes, very much so. Your boiler is of the 'copper tube heat exchanger' type, and they are very sensitive to the proper flow across the boiler. The sounds you describe are indicative of low flow across the boiler. When the system is making that noise, open the bypass... I will bet a few beers that the sound goes away almost immediately, let me know if I'm right!

The "specific <30f inlet-outlet temperature drop" is important with this boiler, so your purchase of the thermometer is a wise one.

Is the bypass piped according to the diagrams in the manual? As a SYSTEM BYPASS, meaning that the circulator pump is between the boiler and the bypass pipe? If the bypass is between the boiler and the pump, it will not help at all... it is wrong for this boiler...

A bit more on the pinging... when the system bypass pipe is opened, the radiators will heat more slowly, and the pinging may be reduced substantially.

A bit about the use of IR thermometers... they are very handy, but one must understand something about them in order to get reasonably accurate temperature readings. Different materials have different 'emissivity' properties. In general, shiny objects will not register accurate temps. Therefore, pick up a can of flat black paint, and PAINT THE SPOTS you intend to measure. You can also use black electrical tape, but the paint works better. In ANY case, make sure that BOTH spots are treated the same way... because even if the ultimate accuracy is not perfect, at the least, the DIFFERENCE between them will be reasonably accurate.

 

Hi Grady! ... not as temperamental as me after too many !

Oleg, try to shoot for about a 20° temp differential. You may find that over the course of the winter that diff will change with the load on the system.

 

An update:

I opened the bypass a bit as I was leaving the house and the noise hasn't been heard since. Yesterday I had time ot "hunt" it a bit to make sure that's what was causing it. Didn't take long. I closed the bypass and turned up the thermostat. Almost instant humming. Ran over to the bypass valve and about 1/5 turn did the trick instantly. So, even though I never accepted the bet, a few rounds on me if you guys are ever in NYC and want to call it in!

I'll tape up a few points on the pipes and take the measurements as you suggest. I guess I'll have to repeat once it gets much colder... Does it matter much if I'm measure the supply and return thicker pipes directly on the boiler or the thin pipes for each zone?

Once I get that set I'll see if I need to return to your suggestions regardign the pinging.

To answer you questions they are Slantfin brand fin-tube baseboards and pump is installed correctly.

 

Great! now I don't have to give up any beers!

Measure close to the boiler, and strive to take measurements on the same TYPE of pipe also. If some pipes are copper, and others are steel, you can't really compare those readings without possibility of error in the readings.

Is the bypass valve a ball valve (lever handle, 1/4 turn), or a globe valve (round handle, multiple turns) ?