Vanity - Little help with a boiler question

Self | 11/24/10 | Self

[mark3681]

Have a question on flushing my boiler.

[mark3681]

Anyone out there that is familiar with home heating hot water systems that could help me out would be greatly appreciated:

I am renting a home that has a very old hot water heating system. Natural gas powered boiler, baseboard galvanized pipes.

Last year the system didn't heat very efficiently. I'm sure this is due to its age. However, per my landlord, the system hasn't been flushed out since he's owned the place, about 5 years.

I have an expansion tank in the basement ceiling. Hot water to the radiators is supplied through it. I have a circulating pump for the cold water return.

According to what I have read all I have to do is open the blowoff valve and let the water flush through the system. For this to occur I would have to leave the water supply to the boiler open to flush clean water through the system. My questions are:

1 - There is no blowoff valve. There should be one located between the circulating pump and the boiler. Where this valve should be is just capped off. I am considering removing this cap and installing a valve.

2 - Does the boiler have to be operating to perform the flush?

Any help would be greatly appreciated.

[palmer]

I know nothing about it but my instinct is to turn off the system, especially the heat. I just installed a water heater and they made it clear to get all the air out of the tank and lines before applying power to the heating elements. Running them dry would quickly burn them up.

[mark3681]

Thanks for the input. I believe that would apply to electric type heating though. With no water to absorb the heat from the element, yes, they would very quickly burn out.

[eastforker]

Just my 2 cents worth but if you are renting, why not make the landlord fix it? Also, is this a true boiler system with steam or just hot water?Also I would think there would be some sort of trap/filter/screen in the system. If there is a calcium buildup in the pipes I doubt simply flushing will clean it out.

[mark3681]

By the way, this is very similar to what I have. The system does not supply hot water to any faucets (as shown in the pic). Hot water to the faucets is provided by a standard gas water heater.

[Tuscaloosa Goldfinch]

I would think it would be your landlord’s responsibility to have it repaired for you.

[marine86297]

I am a mechanical contractor and we work on boilers. There is more to flushing a Hydronic heating system then just opening a valve and letting water flow through.

The landlord should hire a reputable company to come in and perform this for you. A good service company can go through the boiler and perform a seasonal inspection for you. By just uncapping and letting water flow, you may actually introduce air into the system and then you have another set of issues.

[eastforker]

Good diagram. Check that flow control valve for an onstruction, also check for settlement in the expansion tank.What size pipe is used going to the radiators?Also, check water temperature coming out of boiler to see if the water is being heated to operating range.

[mark3681]

Yea, I know. I got a deal on the rent in exchange for taking care of minor repairs like minor plumbing and electrical problems, etc. When I first moved in I had to pull the toilet and replace the flooring under it, as well as repair the floor beams in the basement. He pays for any materials I need, I just provide the labor. It’s a win-win.

[boxerblues]

Contact a HVAC company for about $79 they will come out clean the boiler and flush all the lines and bleed all radiators and make sure you don't have any other problems...if the landlord wont reimburse you it is still money well spent

[mark3681]

Couldn’t I take care of the air issue by opening the bleeder valve on each radiator?

[CJinVA]

1.) First thing you need to do make sure you have a pressure relief valve right on the top of the boiler.
2.) I don’t think you’ll gain anything by messing with the flow of water through the system. That’s probably not the problem. More than likely the problem is the flow of exhaust gas through the heat exchanger in the boiler. You need to get your boiler tubes cleaned. The hot exhaust gases from burning the natural gas exit through burner tubes that are surrounded with a water jacket and up out your flue. The heat is transferred to the water for circulation through your radiators. The tubes get clogged up reducing the heat transfer. You need to hire a HVAC guy.

[Thermalseeker]

I have several hydronic radiant floor heat systems that I have installed in my buildings and for neighbors. It's not exactly the same as what you describe, but it's close enough to give you some ideas.

You should definitely have a blow off valve. Not having one is very dangerous.

Flushing the system might not be necessary unless you have a scaling or rust issue. Mine has been operating for over 15 years and I've never flushed it. My system is a bit more modern than what you describe, but mine does have ferrous components, i.e., boiler jacket, pumps, etc., so rust is something I keep an eye on. If you do flush it you will need to add back a rust inhibitor and propylene glycol antifreeze if you ever have a situation where you might leave and the heat could go off for an extended period, allowing the circulating fluid to freeze and damage the system. Anyone who sells boilers will have the rust inhibitor (I think Grainger sells it, too). A chemical supply house with have propylene glycol.

Most likely your system has air in it. Sometimes if the water level gets very old the boiler will sound like a child crying or a cat screaming when it is at operating temperature. If the system has air in it the shortest, highest lines in the system will vapor lock and greatly reduce the heating efficiency. Your system should have an expansion tank and a vent of some sort to vent air out of the system. When mine gains some air, usually about once every two years or so, I add water and bring the system pressure up to about 15 psi while circulating the boiler. This helps to force air out the vent. You should also check your pumps and make sure they are all working properly. Most systems have at least two pumps, one for the boiler loop, and one for the system loop. There may be other pumps, depending on how complex your system is.

In any event, it sounds like you have air in the system.

[Jaysin]

you can free estimates from a plumber (depends were you live) at http://www.plumbingnetworks.com

I know that all of the contractors are licensed. It’s free and you can get more than 1 quote and choose the contractor that you want.

[osagebowman]

Our circa 1903 house has hot water heat and radiators.
We’ve lived in it for 34 years and the only time we’ve had to flush the system is when we’ve had work done on the boiler unit. There are not many things to go wrong with a boiler outside of it springing a leak or the thermocouple going bad.

To properly flush the system, the valves on the baseboard radiators will need to be open to get the system to drain.

Have you tried bleeding each radiator when the system is on? There could be an air pocket or two that is preventing the system from filling properly.

If you have an automatic refill valve, it could be stuck in the closed position and there is not enough water in the system to fill the radiators. We replaced our existing coal-converted-to-gas boiler in 1982, and the automatic refill valve froze last year on the ~new~unit and had to be replaced.

Just some things for you to check.

LSAggie (posting on hubby’s account)

[Tuscaloosa Goldfinch]

Oh, okay. Well, I hope you get it repaired soon. Maybe a plumbing supply house employee would have some advice - they are pretty knowledgeable.

[mark3681]

79.00 sounds like a deal. I left a message for the landlord yesterday. Waiting to hear from him.

I just thought, if this was easy enough, I could save him a few bucks. Things are really tough for him right now. He’s been out work for over a year. He’s trying to hang on to his house and this one.

My situation is better, but not by a lot.

In any event, I appreciate everyone’s input. Sounds to me like it would be safer for me to bite the bullet and let someone come in and take care of it. Probably cheaper in the long run too. God forbid I’d cause some major problem and end up with a real mess on my hands.

Thanks to all.

[mark3681]

Thanks for the info. I think I’m going to just bite the bullet and let someone come in and take care of it. The more I look at this system the more nervous I am about messing with it.

Have a great thanksgiving!

[bert]

Bing is my friend

http://www.diydoctor.org.uk/projects/drainch.htm

There is also a video

These instructions are for an open vented system only. If your system is sealed please find a qualified plumber. For more ideas and information regarding central heating look at the rest of the central heating projects on this website. Click on any of the blue links to get more information. Before reading this project it is worth thinking about the heating system you have. If your boiler is over 10 years old you could be wasting half the gas you buy!

Sometimes it is necessary to drain down a heating system. This may be because you need to introduce an agent to clean it and flush it through, removing sludge etc or simply to change a radiator. In all events it is necessary to turn off the boiler. Turn off the gas or electricity supply to the boiler or in the case of a back boiler or solid fuel, make sure it is out. If this is necessary more than recommended you might like to have a look at the effectiveness of your boiler.

In your loft you will have a tank called a feed and expansion tank. Its recognizable by a pipe coming in at the top which is the expansion part of the equation. If the water gets too hot in your system the steam can expand, via the pipe, into this tank.

The water is fed into this tank from the mains via a ball valve. This valve is the same as the one in your toilet cistern ( see our tanks and cisterns project ) When the water rises it lifts the ballcock. The ball is attached to an arm which closes the valve when it is lifted. When the tank is full of water, no more can
Radiator Parts

get in because the valve is closed. When some water is drawn off, the ball drops, the valve opens and water rushes in to replace it.

To ensure no water comes in while you are draining the system down it is an easy job to place a piece of timber across the tank, lift up the valve arm and tie it to the timber. This will close the valve.

Now connect a hosepipe to the drain nozzle (marked outlet on the top image) and run it outside to a suitable point. Make sure, especially in winter, that the water does not run onto the road or pavement where it could freeze and cause accidents. Open up the drain valve and let the system run through.

The water will run faster if you open any bleed valves on the radiators starting with the radiators at the top of the building. As the water level drops you can open the bleed valves in the downstairs radiators also. New valves and tools can be bought from the tool store below.
Tank Parts

When no more water comes out of the hose you must check that the system is finished before you remove radiators or start work. There is a chance that some air has got into the system and locked the water from escaping. Go into the loft and fill the tank with about 6 inches of water by loosening the arm you have tied up. This should, in a few seconds, start running out of the hose. If it does not you have an air lock and should connect the other end of the hose to the cold tap and send a short blast of water back into the radiator you are draining from. Make absolutely sure the hose is well attached to the radiator drain nozzle.

Refilling the system

Close the drain cock on the radiator and all the bleed valves that you have opened. Untie the string in the feed tank and let the water fill up the system via the tank. Wait until the tank stops filling and go downstairs to bleed the bottom level radiators. When they have been bled repeat with the top radiators upstairs. This should ensure your system is filled.

Double check the work you have done to ensure you have re tightened all nuts etc and turn on your power supply and relight the boiler. As the water heats up you may hear some knocking sounds as any air expands in the system. The radiators will probably need bleeding again once the system is fully heated.

Once the system has reached full heat/pressure, look at your work again to check for leaks. If you want to have new radiators fitted while the system is drained down, or if your old system is not up to scratch, click on the images left and right to get an unbeatable deal.. Click into the tool store below for all the tools you need for your project.

You might like to go to our video section on draining down and watch the “draining down” film that shows how to drain a central heating radiator.

[Born to Conserve]

Too many variables. When you say “didn’t heat very efficiently”, what do you mean? Did you measure the flue temperature, or did you just think the house was cold and drafty?

You need to get someone with knowledge in you basement.

Loving old things, this is hard to admit, but getting a new, high efficiency water boiler would probably be the most efficient thing you could do. Properly installed, condensing systems are amazing.