Laars Mini therm, no bypass, no air vents, purge problem


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Old 02-06-09, 02:34 PM
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Laars Mini therm, no bypass, no air vents, purge problem

Hello there,
I read this forum and I'm really impressed about the level of knowledge and passion that you guys put in.

As you can see from the picture, I have a JV minitherm installaed back in september 2008 that replaced an old boiler from 1976.
Basically, almost no modification was done to the old pipes to accomodate the new boiler nor air vent or bypass was installed.
The installation was done by the a plumber with basic knowledge of heating system (as he said) but he is an old friend and now he has family problem and can't finish/fix the installation.
The system was working with a pressure of 12 psi when cold and about 15 when hot.
At the begin I had to purge some air in order to eliminate a loud noise (like a little airplane), kind of vibration
I have to leave one zone manually open upstairs otherwise when only one zone was open (upstairs) the noise would be stronger.
Basamens is one zone and works correctly, upstairs as i said the two zones have some problem working alone due to probably some big sac of air stucked.
Basically I want to flush the system (the plumber didn't do it), Ive noticed that when I bleeded a couple of baseboard, the water that comes out is dark brown.
I want an opinion from you guys, if the system is safe, I read that without a bypass valvle the boiler can have a premature failure, also no air vent etc etc.
Boiler stops around 160F, aquastat's dial is @ 220F

Now if I flush the system (one zone at time), do I need to keep the circulator on or can it stay off?
Can I use the drain on the return or should I use the drain on the bottom of the boiler?
Ive noticed that if I raise the pressure limiter to allow full flow of water the pressure raises around 20psi, after I close the lever, should I use the pressure relief to lower the pressure back to lets say 12-14 or should I keep using the return drain?



Thank you for your time and answer

Have a great weekend



Laars Mini therm, no bypass, no air vents, purge problem
 

Last edited by Pinuz; 02-06-09 at 02:53 PM.
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Old 02-06-09, 04:55 PM
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Oh boy...

Pinuz... I'm not sure where to start... You have apparently taken the time to do some research here and I applaud you for that! I'm sorry that my advice is not good news.

Let's talk about the bypass first.

As you have read, your boiler is of a type that is VERY sensitive to having the proper flow through the boiler. You MUST install the proper bypass piping. It is likely that at least SOME of the sounds you are hearing are because there is no bypass.

The green circulating pump is installed improperly. The motor shaft must be mounted HORIZONTALLY. It is possible that this is causing some noise in the system.

I do not see an AIR SEPARATOR on the system and that will lead to problems with air bubbles being impossible to remove from the system and always adding to the noise.

There are other problems also with this installation, and I will not point them all out at this time... but to make a long story shorter, my suggestion is to start over. Take the manual for the boiler and read and understand it. There are diagrams for piping this boiler in that manual and you MUST follow them. The boiler will have a short life and you will be very unhappy with the results if you don't.
 
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Old 02-06-09, 05:06 PM
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OH, and TURN DOWN the aquastat setting to no more than 180F, that temperature of 220 is TOO HIGH!

But where is that aquastat mounted to? I believe that is an AUXILIARY high limit control? There is another temperature control inside the boiler, so perhaps the setting on that other aquastat is correct... it is difficult to see. If there is a red pushbutton that I see on the cover, then 220 is probably the correct setting... (or close to it).

I don't believe the gas piping is installed properly... but I can't see enough of it to be certain.
 
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Old 02-06-09, 06:27 PM
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Thank you so much for your answer, I didn't expect an answer since I knew that many things aren't right.
Yes, before posting I read the forum
The aquastat has the red reset button and the boiler had the temp set to 160.
I purged "some" air but never in the proper way.
Soon I'll have some time/money to redo' the piping properly, for now I only need to get out most of the air and be sure that the pressure is fine.
The hummm/airplane noise was gone when I let some air out.
When I started using the kitchen/living room zone for the first time, the boiler shaked like it was breaking, so I shut it down right away and realized that too much air was on it.
Tomorror I want to flush the entire system, if you can please confirm or correct what I'm going to do

1) shut down the boiler
2) close the 3 zone except the first I'll flush
3) Manually open the first zone valvle
3) open the drain (blue or the one on the bottom of the boiler?) and at the same time slowly open the lever to let the cold water enter full flow
4) I'll monitor the pressure lowering the lever if needed
5) when no air I'll close both and start with the next
should I let the circulator run?
6) will do the other two zones
7) when all done I'll leave the lever so the inlet will go back to 12 psi and at the same time close the drain.
13) I will lower the pressure to 15 psi max using the pressure relief or the drain
14) I'll start the system leaving the drain little bit open to allow other air to escape

I dont' know If the procedure is correct.......

If I keep the system running with low air, the boiler should be ok without bypass at least unless I can repipe.
Will the circulator be ok in that position or can be damaged?

Last thing, the gas pipe is hanged on the joist and the fitting was done by the plumber, I can post another picture.

I see this forum is huge, I'll probably start helping people in some area where I can be helpfull, making people happy pays your soul.
 
 

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