Repair or Replace Gas Boiler

bigjohnnymack · March 6

Hi , my 30 year old teledayn lars

FHW natural gas

boiler blew up the t & p valve , copper tubing it was soldered on right off the boiler .

Prior to that , the second floor baseboard lost its heat.

First floor baseboard was still giving off heat. Boiler operating and heating.

Running like that for 4 weeks.

When one evening a loud explosion occurred in the basement.

Upon checking, I found the boiler not running and a little water around the boiler.

Looking further, I saw that the T & P valve had blown right off the boiler top.

Is the boiler repairable ?

By repiping a new T & P valve to the boiler and flushing and purging the air out of the first and second floors baseboards.

Then restart the boiler and do a boiler check.

( What causes the second floor baseboard to lose its heat ? )

Air in the system ?

Water filled evaporator tank ?

Clogged water feed valve ?

Thanks

John M.

pecmsg · March 6

https://forum.heatinghelp.com/discussion/200854/repair-or-replace-gas-boiler

Are you\ saying the threads where the TP relief screws into the boiler stripped and the entire valve shot out?

EBEBRATT-Ed · March 6

Sounds like either you don't have a low water cutoff or the LWCO did not work.

The boiler should be inspected for damage. If it looks like it may be ok it needs to be disconnected from the system and a hydro test done to check the heat exchanger.

Thats for starters

Jamie Hall · March 6

It may or may not be salvageable — I wouldn't say repairable. I wouldn't bother; too much more or less difficult to detect damage may have been done by the overpressure event.

In fact, I would scrap it, the expansion tank, and any trim, such as the defective pressure relief valve, the low water cutoff (if there even was one), aquastat controls — the lot. Again, not worth the time and effort to find out which redundant safeties failed.

Then start all over again.

Mad Dog_2 · March 6

You got a long run out of that Tlyne-Laars...That's not even a company any longer, but Laars make a really nice replacement. Mad Dog

mattmia2 · March 6

Could be the expansion tank was waterlogged and the relief valve was scaled shut. Could be system was low on water because the pressure reducing valve failed and it had a leak of some sort and the boiler got low enough on water that the boiler heated the joint on the relief valve to the point where it melted the solder because part of it was dry firing. In either case it would be best to replace the boiler after either event.

Did water pour out of the relief valve piping?

bigjohnnymack · March 12

https://forum.heatinghelp.com/discussion/comment/1847008#Comment_1847008

* Thank you

Yeah The T & P valve and valve pipe it was affixed to shot right out of the top of the boiler . . Exploded boom.

bigjohnnymack · March 12

https://forum.heatinghelp.com/discussion/comment/1847009#Comment_1847009

* Thank you

bigjohnnymack · March 12

https://forum.heatinghelp.com/discussion/comment/1847012#Comment_1847012

* Thank you

I tend to agree .

Get a replacement gas boiler.

Any suggestions on brand gas boiler.

Thanks

bigjohnnymack · March 12

https://forum.heatinghelp.com/discussion/comment/1847044#Comment_1847044

* Thank you

That Tele Larrs boiler was a good boiler. 30 + years old.

It was used in heating swimming pools.

Thanks

bigjohnnymack · March 12

Thank you

Sounds about right on.

Probably scale clogged the

Valves And T & P.

Low Water - then hot steam -

Boom - T & P Valves and valve pipe shot out - exploded.

Looking For Replacement Gas boiler. Burnham , Weil McClain , Crown , Utica . .

Thanks

mattmia2 · March 12

I assume it uses a HX to heat the pool water?

EBEBRATT-Ed · March 13

You should probably stick with the same type boiler if it worked. Larrs or RayPac also make them

Mad Dog_2 · March 13

Laars makes a great product & fantastic tech support & warranties. Mad Dog

bigjohnnymack · December 15

Yay Good News

30 year age Teleydine Larrs 130k btu boiler repaired

up and running - heating house.

Plumber boiler tech

new valves

replaced the pressure reducing water feeder valve

replaced pressure relief valve

replaced expansion tank

installed air vent on water supply feed ( never had air vent valve )

replaced vent ( chimney pipe )

valves replaced had clogged up over 30 years of use and no maintenance checks

clogged up valves caused water blockage depriving boiler of water

causing steam buildup

resulting in clogged pressure relief valve malfunction - with pressure relief valve explosion shutting down boiler

price of repairs $1,200 -

* still no low water cut - off valve

never had one - can a low water cut - off be installed

happy repairs thanks all

bigjohnnymack · December 15

Lesson learned . .

do annual check up on boiler by

HVAC plumber tech

* if the FHW baseboards are

sounding like you hear water gurgling thru the baseboards

( air in the pipes )

and no heat to separate zone to the second floor of house

when operating the boiler

it's time to call the HVAC plumber tech

to avoid boiler shut down

bigjohnnymack · December 15

Question . . December 15, '25

the city has contracted a utility contractor to take out from the street to the house the old water supply line and replace with a new water supply line , from street to house

With the disconnecting of the main water supply feed to the house cause damage to the FHW gas boiler and gas hot water tank ? ? ?

What precautions should be made . .

Shut down the boiler and hot water tank ? ? ?

While contractor disconnects old water line and installs new water line ? ? ?

If shut down gas FHW boiler and hot water tank.

What has to be done to put the gas FHW boiler and hot water tank up in running . . .

any bleeding air out of the systems required ? ? ?

I told the city why is the work being done at the beginning of the heating season , in middle of December - with temps in the teens o's . . when the house needs an up and running heating system.

I told the city to do the work at the end of the heating season . .

thanks for any advice

hot_rod · December 16

the boiler should have a fill valve with backflow preventer. As such the water and pressure in the boiler should not be affected by a water line shutdown. Unless the heating system has a leak?

It’s possible the entire home has a backflow device or a PRV that acts as a check valve?

The low water cutoff on the boiler would be the next layer of protection. That could be a probe into the boiler, or even a pressure switch which cuts power off to the system drains or drops below a pressure. It prevents dry firing, should the boiler drain completely, which is rare.

Or just risk it, and do nothing.

mattmia2 · December 16

turn off the hot water heater but the boiler will be fine unless you have a huge leak in the system.

mattmia2 · December 16

test the pressure relief valve regularly. lift the handle and see if water comes out and if it stops when you release the handle. do it when you don' need heat so if it doesn't shut you have time to replace it. make sure the pressure reducing valve keeps the system pressure up after doing that. not a terrible idea to just replace the relief valve every 5-10 years either.

Repair or Replace Gas Boiler

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