Oil-Fired Boiler Troubles---Need Help & Advice

Well, the house certainly needs a whole-house filter on its inlet main, though that might not be the cause of this particular problem, Captain, as the circulating loop tank would be full of sand too.

I'd start by chasing-through the control circuit. In a pumped-circulation system, there are often zone valves that divert the circulating water from the boiler to various parts, including the coil in the DHW tank. If there's a loose connection, or if the tank thermostat is inadvertently set too low, then the port that covers the tank coil pipe in the valve will be closed when you want it open. Chase it right back to the programmer and out again to the boiler run wire, and see if it's energised when you want DHW.

It is not unknown for a diverter valve to be stuck, and changing its actuator might be the solution.

Do this check before getting the tank coil changed!

Hello Crabtree,

I'm not sure that we're talking about the same type of household boiler. For my boiler, there are 2 independent cold water inlet (feed) lines: one for the DHW and the other is for the makeup water to the boiler tank.

I'm not sure what you mean by "control circuit". Also. where would the zone and diverter valves be located? Where is the tank thermostat located?

I'm not qualified enough to open up this boiler.....

If I obtain the boiler manufacturer and it's model no., do i stand a chance of locating a manual or schematic online, say through Google?

Thanks in advance!

What kind of psi do you have on the incoming line? Are you sure that is sand and not calcium from the boiler. A fix if it is plugged is muriatic acid in your DHW line that will clean the copper pipe. Hope this helps.

I would think that the Culligan would take care of the Calcium issue. I also do not think the heating loop for the house would be clogged as it is a some what closed loop if you are running base board. If it is steam then any particulate would accumulate in the boiling tank and could be bled off by the drain valve.

I can easily see the DHW heating cartridge getting clogged. Once removed ask the tech to keep the loop and try back flushing the unit with the garden hose. I would bet you will be suprised at the amount of debris the get washed out.

Do yourself a favor and install a home water filter system. I had to do this years ago and I change my filter every 2-3 months. I is usually filled with small grains of sand and silt from the well.

good luck

Bob

I lived in a house with a system like yours. It got real slow, didn't make hardly any hot water. Instead of fighting with old pipes and disturbing the old monster, I just put in a nice gas hot water heater. It was easy enough to plumb it into the lines, and I just turned off the valves to the old unit.

Venting the gas heater was tricky, I ended up just removing a pane of glass from the basement window and running the vent out there, cut a piece of tin to fill the difference. I don't know if it was code, but at least it was outside.

My new wife was tickled pink. She never had so much hot water. I got the heater used, and the house already had gas for the stove. If you go this route, have a qualified plumber do the plumbing, especially the gas pipe, some trade tricks there.

Yes, your problem is sand clogging up the coil. This type of problem is often seen with tank type water heaters. Water comes in with enough velocity to keep sand suspended in water, velocity reduces to nil in the tank and the sand settles out and collects in the bottom of the tank. Take 35 gallons of sand in the bottom of a 40gal heater tank and you don't have much water capacity and also have a poor thermal conductor sitting next to the flame. Ends up with very little hot water both in temp and volume.

Whole house filter rated at 10 micron, the standard size available at the big box stores for removing dirt will work fine. If you have plumbing skills, suggest you you put two of them in parallel with isolation valves so that you don't have to shut everything down to change filter elements with the chance of sand getting by the filter. 1 micron units are used for very extremely fine silt removal. 10 micron will get everything that could cause a problem.

Good Luck

First you give a very poor view of your problem.you say"Only a very small amount of hot water is making it to the faucet"" So is it you little volume of hot water or is it the temp. of the hot water.Is it a "COIL" in your boiler,or a side arm heater.Im going to go with a hot water coil.and the Temp. of the water not the volume.It sounds like the coil is getting scale build up on the inside of the copper pipe that make up the coil.Yes you can "Flush the coil out with acid" and HOPE that it will work.Most likely it will get just a little better,but not much.The best bet would go for a new coil. But you say the boiler is OLD. So that must mean that you may be better of replaceing the whole boiler. If you have a 1750RPM motor on the oil burner,then that is wasteing alot of oil,and if its over 10 years old it could start to LEAK inbetween the sections. So you will Dump $500.00 or more into it now,and if its old you might dump in another $500.00 next week. who knows.Coils are about $300.00 labor????$200.00 :New boiler about $2000.00 labor??? $1000.00 But you will save alot of money each year with a new Hi Eff. boiler.{wet base]. When i use to do work for people and they watched over me like you said you were going to .I use to say,Well Im going for coffee.Just hate people hanging all over you while you work, and ask Dumb questions.

I did plumbing/heating/remodeling/building/etc.

Good luck.

Hi Guys,

Thanks for answering my post!

I guess that I wasn't clear in my description, so here's some more info:

The boiler is approx. 18 years old, and is fuel-oil fired. It produces heat for the DMW as well as the Hydronic radiator system to heat the house. The unit is producing heat for the house as I type this......45 F outside and 68 F indoors this morning at 8 AM. There is NO stand-alone how water tank for DHW production.

When I said hardly any hot water is coming out of the faucets I meant that the stream flow was very low (about 1 gpm) with a very tepid temp (about 70~75 deg F) & pressure less than 20 psig. The cold water flow at the kitchen faucet is very good (over 5 gpm), w/ pressure about 50 psig.

The pressure on the service lateral as it comes into the house is about 60 psig.

I hope this helps......

Forgot something....

And yes, it is silicia sand, and not calcium, that has been clogging up the system......as stated before, I have a Culligan Water softener installed before the boiler to take care of the Total Water Hardness that the Village Water Det doesn't get with their treatment trains.

You mention that you have a water softener. Note that a water softener will act as a filter for incoming debris of the size you report finding in the aerators. I would suspect a faulty softener if material that size is getting through. If the water softener collector goes you would also find the softener beads in there as well. If no beads I would check the riser pipe in the softener tank or a problem in the softener valve.

From your post it is not clear whether the hot water flow is low or the temperature is low, please clarify.

Moosie,

It appears you answered my questions as I typed my previous post. I believe that your problems are related to the softener. At present at seems that you HW coil is obstructed and insulated either internally (most likely) with calcium (the softener should be preventing this) or externally with soot/carbon. Removal will reveal the problem. Good luck and keep us informed of what is discovered.

Hello Abner,

Thanks for your advice. I don't believe it is the water softener....I turned it off about 7 months ago since the Total Hardness in the Village water is only 110 ppm, so the softener wasn't really needed and a waste of money.

Anyhow, before and after the softener shutdown, there's been no change with the clogging-up of my faucets, shower heads, and the dishwasher hot water feed line (at the solenoid valve/screen).........all clogging has been made by angular SILICA SAND, not calcium. I know the difference between the two. Even muriatic acid or CLR will not dissolve it. Under a microscope I can see the crystals, which I believe to be Quartz.

Nope, the problems lies inside the boiler or possibly a diversion valve on the cold water feed line (that feeds the DHW system) before it enters the boiler.

Thanks again!

Put a screen in the feed-line.

Normally, the heating coil that brings hot water from the boiler to the hot water tank does not contain calcium since the cicuit is closed and the water should have been treated with additives. The make up water replaces any evaporation or losses to that circuit. therefore, the heating coils should be clear from the inside.

Now if you are using a system that heats the hot water directly, on demand (No Hot water tank), and the stream is weak at the hot water faucet, then the coil that goes into the boiler for hot water only direct circuit, is clogged and need changing or de-clogged(?). by the way, Muriatic acid = Hydrochloric acid = HCL and need proper handling to dilute to ~ 5 times befor using it(!?).

Also by the way: Silica can deposit on pipes in combination with the calcium to form an even harder scale to dislodge!! You said that the hardness of the municipal water is ~110 ppm. This is not low and can be checked on your hot water kettle if there is any deposits that makes you see some whitish scale. The Softener was doing, as said by a previous contributor, the job of filtering some of the silica that is carried in the water while softening...

IF the system has a HWTank heated by a closed circuit hot water from the boiler, then the hot water should only be cooler or gets cold quickly but the stream sould remain at its same pressure. see previous contributor about sand accumulation in the tank.

I am one of those HVAC guys. The fact that you have heat, means the boiler is working. The heating loop for all practical purposes is separate from all potable water sources. The domestic cold line that goes to the heating side is your water make up. It should have a backflow preventer and a pressure reducing valve. Its purpose is to provide make up water for initial filling and leak replacement. If all is well with the heating loop, than no water will be going into the heating system, therefore no sedimentation problems.

Your domestic hot water (DHW) from what I can gather, consists of a secondary heat exchanger in the boiler, probably combined with a storage tank, a circulating pump and some form of controls the whole system.

The sediment that you mentioned will definitely be a problem. Am I to understand that you have a volume problem? Poor flow.

Hot water can not hold dissolved minerals well. Clear normal water going through a heating coil should not be a problem. However, when the water does not move the minerals can precipitate out, as the DHW loop is in a permanently heated boiler. Toss in fairly large particles and you have the makings for cement.

No general domestic system is designed to tolerate a large volume of sediment. Your inlet screen on the dishwasher is there to protect the solenoid diaphragm. It is the last line of defence. The fact you have to clean it, indicates a serious problem.

The water filtration system you mentioned will solve the incoming sediment problem, as any thing better the four microns is considered great. Unfortunately it is just a bandage, and you will be either spending time cleaning it, or money for new filter elements. Your problem is out side of your residence. Sediment in city water is not normal. In my region the government has posted rules for water quality. Your water would fail, due to the sediment.

Hello Icarus et All,

Well, the repairman was here and yanked out the DHW coil and it's full of silica sand.....just what I thought originally. The hot water temps and flow are great now.

I only have to install the inline filter now (today) to prevent clogging up my water lines, faucets and the boiler any further. And flush everything well today!

I believe the sand was coming from the water main repairs that the village did a few months ago on a leaky section of PVC water main. No doubt they didn't flush the main after this repair.....I'm home 24/7 on Disability and would have noticed the hydrants being flushed.

So, that ends this saga. I thank each and every one of you that responded...all a great help!

I see you fixed your problem but also a nice y strainer on the inlet of the coil would not hurt. this would allow you to check it it periodically for any sand and a good way to flush the lines before the coil.

Thank you for ending the story properly.

Hi Guy .................. on your closed loop boiler system, you should make sure that you charge the system with the proper fluids. If you have a tight system all the oxygen will vent out and your system will maintain 20 lbs or so for a long time. This means that there is no flow past the backflow or the prv, and they clog up and are a pain. Oxygen is a very very hard element of water, and it will come out of solution and be thrown out, when it changes direction. It will eat a pin hole in copper pipe in no time. I have seen boiler systems with a drippy pop-off valve go un noticed for quite some time, every drip drip out is a drip drip in, and so you have oxidation/degrading constantly going on, and will cut years off of your boiler system. so a good closed loop system does not take much maintenance since it has no oxygen to clog things up. But on the other side the sediments and sand are a big problem and must be brought up with the purveyor of your drinking water. Quite possibly there are others with similar problems. A good test of your water will show you that soft water is not what it's cracked up to be. A filter can be designed for your home and the bottom of your DHW storage tank kept flushed. Good drinking water is a must. I hope this helps you.