Options for Heating Replacement

fusion327

Looking for some guidance on heating replacement given that our family hasnt had any experience dealing with it.

Current Scenario: Need to replace the heating in a 2600 sqft house (over two floors) because heating makes loud banging noise from trapped air bubble. The issue goes away quickly after changing the bleeder valve but it happens again very quickly. To our knowledge, the heating solution hasnt been replaced in 30 years. Location is Pacific Northwest in Canada.

Current Hydronic Radiant Heating with a gas boiler in the boiler room in the garage
- Ground floor in floor radiant heating
- Second floor is baseboard radiant

1. Is it advisable to still reuse the existing hydronic radiant piping given the old age?
We are inclined to keep cost low - thus tempted to reuse the existing piping. However, we are scared of leaks given old age. Are we setting up ourselves for more trouble down the road?

2a. If yes to reusing existing piping, are there affordable checks that can be done to check for leaks or condition of piping? Or are there things that prolong the life (i.e. sealants, epoxy lining, etc?)

3a. If it does leak in the future, what are the costs usually to fix the leaks? (I am guessing the in floor piping will be most costly)

2b. If no to reusing existing piping, what are advisable and cost efficient replacement options? (We only really need heating for now) Would mini split ductless heat pumps be a good option (they seem to be gaining popularity). But for a 2600 sqft house (with 6 bedrooms and common area), it seems like I'll need at least two full size units, each with 4-5 zones) and it would be quite costly.

johncharles

When was the house built? 30 years for hydronic piping is not old. Is the sound a gurgling sound or loud banging? Almost sounds like the boiler could be making steam not good on a hot water system. Have you had the aquastat checked for proper operation? 

fusion327

House was built in 1989.

It starts with gurgling sound then eventually turns into loud banging if we dont manually release the air from the bleeder valve (even though I heard it isnt stuck since it is a new bleeder valve)

Our previous contractor (now retired) mentioned it was time for a replacement given the issues that happen on a yearly basis.

This is the current boiler

Jamie Hall

Air shouldn't be getting trapped. In most systems that new, there is a device at or near the expansion tank which exists quite specifically for that purpose. If you could post a picture of the expansion tank and the associated piping and air eliminator, it would help.

Also, check that expansion tank. If it's failed-- and that, at that age, is a distinct possibility -- it needs to be replaced. There will be a system pressure gauge somewhere near the boiler. It should read around 15 psi with the system cold, and not go up to much more than 20 psi with it hot.

30 years is not old for hot water heating plumbing. Shouldn't have to worry much about it.

pedmec

I think that replacing the boiler without finding out the problem of the banging is a waste of money as the boiler is not the issue. You should never have to bleed air out of a properly operating hot water system unless the system is being opened up. You need to check the fill pressure in the boiler to ensure you have enough to flood the highest radiator in the system. This will prevent air from sneaking into the system thru any air vent. Depending on the type of system if your not moving water thru the system you could possibly be flashing the water in the boiler into steam. Just a small snippet of what could e happening

kcopp

Can we get more pix from further back of the piping?
From your description and the boiler being a Laars design set up makes me wonder if its not piped properly.
there is next to no mas to the boiler and water in it will flash to steam FAST if there is poor/ no flow.

fusion327

First off - thank you for the advice on finding the root cause instead of just throwing away money with a new boiler.

Here are the photos of the system.

- For the expansion tank, I was told to tap the top half and the bottom to see if there is a problem. The top half sounds empty while the bottom half sounds full.
- All three air bleeder valves are relatively new.

hot_rod

I don’t see a central air purger, just a couple brass float vents. If fill pressure is low, air could be entering one of those vents. If you get it bled out and quiet, tighten the caps in the air vents and try it.

It is fairly outdated piping, the blue tekmar mix valve really should of had a motor on it to mix and protect the boiler properly 

some piping updates would be nice, maybe not necessary if you can correct the air issues

A good inspection of that boiler would be wise if it has been running extended cold cycles it could be sooted up inside 

fusion327

Even with manual bleed of the air with the brass float vents, the air never completely gets out. I've tried tightening the caps and air still some how gets in.

I guess time to call in a contractor to look at the piping and boiler (and whether the boiler needs replacement)!

fusion327

Jamie Hall said:

Air shouldn't be getting trapped. In most systems that new, there is a device at or near the expansion tank which exists quite specifically for that purpose. If you could post a picture of the expansion tank and the associated piping and air eliminator, it would help.

Also, check that expansion tank. If it's failed-- and that, at that age, is a distinct possibility -- it needs to be replaced. There will be a system pressure gauge somewhere near the boiler. It should read around 15 psi with the system cold, and not go up to much more than 20 psi with it hot.

30 years is not old for hot water heating plumbing. Shouldn't have to worry much about it.

Is this high in terms of the system pressure when it's hot? Looks to be 25psi

Jamie Hall

Sort of. What I'm really not keen is the pressure swing between cold and hot -- it looks like from abut 12 to about 25. That's more than it really should be.

The tap test on the tank is dubious. If you have a tire gauge, however, there is a brass fitting on top of the expansion tank -- it's a perfectly ordinary Schrader valve. It might be worth checking the pressure. That's the air pressure in the air half of the tank -- and it should be the same as the water pressure (the tank, by the way, should be pressurized through that valve to the cold system pressure -- but that must be done with the tank disconnected from the system and empty, which is not practical without a nuisance). If is lower, or particularly if you get any water out of the valve, the tank is done.

EdTheHeaterMan

All this noise and air purging and other comments lead me to the expansion tank is probably bad or at least the incorrect amount of air in side it.

There are 2 sides to that tank. The water side is connected to a 1/2" tee fitting on what appears to be the fill piping to the boiler return just above the circulator pump. The air side has a Schrader valve fitting on .the other side. The proper way to test the air volume in that tank is to get all the water out of the tank. That can be done by removing water from the boiler until the boiler pressure gauge reads (0) Zero. There is no need to empty the water from the boiler system. just enough to get the pressure gauge to read (0) Zero.

Then check the air side with a tire gauge that will be accurate at 12 PSI. digital gauges are more accurate at that lower range compared to the one that pops a stick with numbers out of the end of the gauge. If there is less than 12 PSI, then add air with a tire pump or compressor. Get the air side to 12 PSI. Once the air side is set, then put water back into the boiler until the boiler gauge is at 12 PSI.

You may need to add more water if, in some fashion, air entered the radiators or the boiler. Allow the air vents to vent any air in the system. Since the vents are in poorly designed locations, you may need to operate the pump and stop the pump several times in order to get much of the air out. Once all the air is out, then close all the vent caps to see if the problem returns.

There are no parts to purchase with this procedure. During this procedure you my find the expansion tank is defective, then you will need to purchase a new expansion tank.

OR

Just replace the expansion tank without testing and hope it is not something else.

I hope this helps.

Respectfully submitted

Mr.Ed

fusion327

Jamie Hall said:

Sort of. What I'm really not keen is the pressure swing between cold and hot -- it looks like from abut 12 to about 25. That's more than it really should be.

The tap test on the tank is dubious. If you have a tire gauge, however, there is a brass fitting on top of the expansion tank -- it's a perfectly ordinary Schrader valve. It might be worth checking the pressure. That's the air pressure in the air half of the tank -- and it should be the same as the water pressure (the tank, by the way, should be pressurized through that valve to the cold system pressure -- but that must be done with the tank disconnected from the system and empty, which is not practical without a nuisance). If is lower, or particularly if you get any water out of the valve, the tank is done.

The tank reads 11psi while the system is around 20psi when hot.

Steamhead

fusion327 said:

The tank reads 11psi while the system is around 20psi when hot.

There's at least part of your problem.

Try this- Shut off the water feed to the boiler. Screw the caps on the bleeders down tight. Connect a short length of hose to the drain- a washing machine hose works well for this. Route the hose into a bucket and open the drain- have a second bucket handy if needed. The system will drain into the bucket as it depressurizes, and if the end of the hose is submerged in water it can't suck air in. You don't need to drain the entire system to do this.

Then get your tire pump and pump the tank pressure to 12 PSI. If you have an air compressor, make sure you don't blow too much air at once. This can rupture the diaphragm. If the tank does not hold this pressure, you need to replace it.

Shut the drain, turn on the water feed, bleed anything that needs it, and see how it works.

pedmec

Something is not right with those readings. The tank, if still connected to system when measuring, will match the the system pressure. The tank needs to be able to feel the system water expansion at all times during operation.

Where is the relief valve discharge tube ending? Can you see if any boiler water is leaking from it?