Low water pressure, and little hot water from my Oil furnace


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Old 10-16-09, 10:59 AM
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Low water pressure, and little hot water from my Oil furnace

Good day all,
I have read a few posts, and I am confident the experience on this site may be able to assist me.
I bought a house here in NW CT in June. At that time, we seemed to have no problem with hot water, in fact I was impressed with the temp, and constance at that time, but the water pressure was a little low, especially upstairs. Since September, we seem to be having a hard time getting enough hot water for a shower, and my wife is complaining she can't relax in a tub of hot water. It is a tankless water heater furnace. I must admit, I moved up here from Texas, and I am not familiar with oil furnaces, or any of this. I have dealt with gas water heaters for years, which are spererate from your heating.
I have adjusted the water temp settings, but it seems to make no difference. The house heats fine, no problems there, so I know the furnace is heating water. But why no hot water to our tubs/showers? I really don't know where to start, and I am not sure who to call if I had the money do do so.
I am wondering if I need to clean the coil?
The pressure on the guage is always bellow the red needle on the glass, and for some reason I feel confident if it had more pressure I would get more hot water. We are on a community well, and I wonder if that has something to do with the pressure.
 
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Old 10-16-09, 12:04 PM
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First, are you confusing pressure with flow? Pressure can be measured under two conditions, static and dynamic. You need a pressure gauge to measure the pressure but you can measure the flow with a bucket or two-quart bottle along with a watch with a second hand.

I suspect that you have more of a flow problem than a pressure problem. If you close down on the hot water faucet (decreasing the flow) does the water get hotter? This is a classic example of a tankless coil that is too small or one that is partially plugged. You may have had sufficient hot water during the warmer months because the incoming cold water was several degrees warmer than it is during the winter months. In some areas the water temperature during the winter may fall to just a few degrees above freezing whereas during the summer months it might be 60 or 70 degrees (or more) and that temperature differential is a real killer when using a tankless coil.

You might be able to have the coil cleaned and get a little more flow or somewhat higher temperature but the real cure is to get rid of that tankless coil and install a real water heater.
 
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Old 10-16-09, 03:47 PM
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A little about the temperature settings on the boiler.

You probably have what is known as a 'triple' aquastat, with three dials inside, labeled HIGH, LOW, and DIFF.

The HIGH setting is the HIGH LIMIT, and has nothing to do with the domestic hot water. It is the maximum temp that the water will heat to during a space heating call. 'Normal' temp for that setting is 180

The LOW setting controls the temp that the water in the boiler is maintained at during non space heating times, and IS related to the domestic hot water production. 'Normal' settings for this are 140-150. This setting should NEVER be set closer than 20 to the HIGH setting.

The DIFF setting is also related to the domestic hot water... and you will get all kinds of debate about this setting... but the best setting is probably 20.

What are the settings you have?

Do you know if there is a 'tempering valve' installed on the outlet of the tankless coil ?

I like one of furd's sayings: " Tankless hot water coils are only better than a kettle on a wood stove " ... or something like that.

We might be able to make some suggestions by looking at pics of the system... free account at Image hosting, free photo sharing & video sharing at Photobucket / upload pics there / place link here for us to view the pics.
 
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Old 10-17-09, 06:08 PM
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I thought tankless water heaters were all the rage?!?! I must have been duped. Unfortunately, I have no funds to replace anything. I don't even have the money to call out a repair man for this. I hope you guys can walk me through it.

I believe you are right, I was confusing pressure with flow rate. The flow rate is rather low in both bathrooms, but especially upstairs. However, I have noted the pressure gauge stays around 10psi. There is a red arrow at 20, so I assume it is still lower than it should be?
Everything I have read, including threads on this forum seem to indicate that the coil needs to be cleaned. I will start with that step. I will try to get some pictures posted, since I am not quite sure how to get to the coil. So far the only maintenance I have done on any oil furnace is changing the oil filter. I was very proud of myself for figuring out that that was the problem, and fixing it. This appears to be a bigger undertanking, ha ha, a little heater humor.
On the front of the furnace is a round metal plate with four bolts. There is a post coming out of it with the aquastat attached there. Also there are two pipes coming out, and the labels in and out. The out is obviously the hot water coming out and going to the bathrooms. There is a yellow knob on this pipe that says anti scald.
I will try to get some pictures posted shortly.
 
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Old 10-17-09, 06:17 PM
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The new standalone, on-demand tankless heaters are all the rage (although FWIW I'm not a particular fan).

What you have is a 'tankless coil', sometimes known as a 'thankless coil'. A little boiler humor, back at ya.

Start by getting some PB Blaster and spraying the bolts.

It would also help us to have the make/model of the boiler.

Somewhere around this forum is a truly excellent thread on cleaning a coil. Maybe a year or two ago. Worth a few minutes searching.
 
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Old 10-17-09, 06:24 PM
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We are on a community well, and I wonder if that has something to do with the pressure.
I'm sure it does, and it follows that if your pressure is lower than a standard 'city' system, so will your flow be.

My private well runs 20-40 PSI, and I can't even get enough water out of the garden hose on the roof to clean my gutters out!
 
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Old 10-17-09, 06:36 PM
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As for a kettle on a wood stove, my neighbor at my last house heated his whole house from a big wood stove with two radiators welded to it. It was rather impressive, so don't knock the wood stove!
 
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Old 10-17-09, 06:42 PM
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I bet it was indeed... and safe too, I'm sure!

There is a yellow knob on this pipe that says anti scald.
That's the 'tempering valve' I asked about. Are there temperature markings on it? If so, what is it set to?

What are the three dials in your aquastat set to?
 
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Old 10-18-09, 02:03 PM
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Well, one of my biggest faults is that I like to dive right into things. I can't get a good understanding of things until I start taking it apart. I removed the aquastat and "thought" I had drained the boiler. Shut off all the water (once again, I thought) and turned off the electricity - not all in that order. I took off all the bolts, and broke the seal. There was a bit of water left, and plenty of pressure. Luckily I was working very slowly. So after I mopped the water up, I pulled the coil out. It is still attached to the pipes, and I can't see a clear way of detaching it without cutting pipes. It is not copper colored, but completely black. I am scrubbing it now, and it is coming somewhat clean. Any suggestions as to what to use to clean this thing?
Two questions arise. If I do need to replace the coil, how do I get it off?
Is my coil to small? there is about 17 inches of space in the boiler for the coil, and this coil is about 10 inches long. would it benefit me to have a longer coil?

NJtrooper, it appears to be set on MAX. the aquastat is now set to 200 and 140, diff is 20

The boiler is a weil mclain
the coil has a sticker on it that says therma-flow inc.
model we-625

Thanks for all of your help so far.
 
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Old 10-18-09, 03:56 PM
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Reads as if you have been busy! The domestic water flows through the coil and when it was first installed there should have been valves and unions installed to facilitate coil removal. Unfortunately it seems that far too many installers just solder the pipes in place and figure that by the time there is a noticeable problems they will be far away.

Since you are on a well you more likely as not have hard water. Hard water will "scale up" the inside of the coil and the only way to clean the inside of the coil is by chemical means. Sometimes simple household vinegar or lemon juice concentrate can remove the scale but not all that often. You really need to disconnect the piping and using a pump continuously flow the chemical through the coil and adding more chemical as it becomes neutralized by the dissolving scale.
 
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Old 10-18-09, 04:25 PM
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Yeah... what furd said... the _*INSIDE*_ of the coil...

At this point though, you might as well go ahead and get a new coil, since you've already got it almost all the way out, and you're going to need a new gasket.
 
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Old 10-18-09, 04:40 PM
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Great, I thought I was really getting somewhere! Where is the best place to get a new coil? Should I/could I get a bigger coil? do they come with valves for attaching, or do I have to find those separate? or should I just solder it on like the last shmuck did?
 
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Old 10-18-09, 04:52 PM
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The coils are specific to the boiler so the first place to check is the local distributor of your boiler.

As for how to connect, you could use sharkbite connectors or you could use a combination of threaded and soldered fittings along with the proper valves or you could do it as it was done originally. Your choice.
 
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Old 10-19-09, 07:07 PM
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Rough day. After tracking down the plumbing supply place, I found they close at 4:30, so I had to take an hour and a half off work. I went with a whole new coil. At this time I have it all hooked up. I used sharkbites. I had never heard of them before you mentioned them furd, but dang, they are worth the extra bux. All is hooked up, and I am waiting for the sealant to cure. Will test in the morning.
 
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Old 10-20-09, 09:00 AM
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I turned all the water back on, and turned on the power this morning. Everything seems to be running well, no leaks where I was working. However, one of the inbound lines has started to leak. It is at a joint high up on the pipe, where a small silver cup like apparatus is. I assume this is some sort of pressure release valve? Will the leak stop, or do I need to replace that piece? I am finding more and more knobs and spigots that seem fine until I use them, and the start to leak.

But as for hot water, lots of it, and very hot! So how do I adjust the domestic water temp on this thing? I understand the aquastat controls the internal temp of the water in the boiler, is that correct? Do I use the anti scald knob to settle the hot water down? One thing I noticed in reading the instructions and parts manual for this boiler, is that it is supposed to have an automatic mixing valve, but that is no where to be seen. Is that something I should consider putting in?
I rather enjoyed this task, and I am feeling more and more accomplished in my plumbing and pipe fitting abilities. I used to be afraid to solder pipe, but I think I am getting the hang of it. The shark bit elbows I put on will allow me to easily remove this coil to clean it next time!
 
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Old 10-20-09, 02:49 PM
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It is at a joint high up on the pipe, where a small silver cup like apparatus is. I assume this is some sort of pressure release valve?
I'm gonna suggest my old standard... show us pictures... free account at Image hosting, free photo sharing & video sharing at Photobucket / upload pics there, drop link here and we'll take a look.

While you are at it, take pics of the anti-scald valve, etc... the more the better.

So how do I adjust the domestic water temp on this thing?
Presuming that you have a Honeywell 'triple' aquastat, inside the a'stat are three dials. HIGH, LOW, and DIFF. The HIGH controls only the high limit for heating the home. Set that at 180. The LOW controls the temp that the boiler will maintain. Set that at a starting point of 140, and set the DIFF at 20.

We do need to see the 'anti-scald' valve though, and hopefully it too is adjustable, and that should be set at 120.
 
 

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