Very little domestic hot water

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Old 04-05-07, 08:55 AM
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Very little domestic hot water

Hi, I'm hoping someone can help me out or steer me in the right direction. I recently purchased a house and the water is heated by a 10-15 year old Utica Starfire II boiler with a tankless coil.

We seem to have a problem with very little hot water available for showers. Pretty much starts out hot for several seconds and then turns lukewarm, then cold, then gets back to lukewarm and occassionally will even be comfortable.

We had a plumber out and he suggests an indirect hot water heater, but our boiler room is not large enough to have one placed in there. To make a long story short, to get and indirect hot water heater in the house would involve a fair amount of destruction of parts of the house that I would rather avoid if I can.

What kind of things should I examine to make sure that everything on the boiler is set/operating correctly when it comes to the domestic hot water? Should I call another person to come out and have a look? When I explained the problem to the plumber he seemed more focused on installing a new hot water heater instead of figuring out whether everything was operating correctly on the boiler.
 
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Old 04-05-07, 03:24 PM
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Tankless coils are a lousy way to supply domestic hot water. There have been numerous threads on this forum concerning tankless coils and their limitations.

If you have hard water the coil is likely encrusted internally with mineral deposits which limit the flow-through of the water. It could be fouled externally which would reduce the heat transfer from the boiler water. There are several other things that could be partially at fault and any or all of them may be present.
 
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Old 04-05-07, 03:27 PM
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DomesticCoil

The type of internal heater you have for your domestic hot water is known as a "domestic coil"; it's simply a coiled piece of copper tubing inside the boiler that heats only 1 or 2 gallons of water at a time for all of your hot water needs.

This is clearly not adequate for more than a family of one person in the household when you consider showers, dishwashers & washing machines; that's why the plumber recommended the indirect heater, which comes in sizes of 20 to 40 gallons, & are much preferred over a domestic coil.

However, getting a 2nd opinion is a good idea; also check to see if there is a defective tempering valve somewhere between the hot water takeoff on the boiler & the hot water taps in the apt.

Do a mental check of your system; do you have "hard" water in your area, with a lot of minerals??

This will clog up the internal coil over time & greatly reduce the amount of hot water produced; the coil can be cleaned by a pro with an acid solution, or replaced with a new coil, but the cost is usually about the same as a low-cost indirect, which is more desireable.

The indirect need be no more than 20-30 gallons if you have a small family, & can be installed upstairs, if needed, in a closet, pantry, bathroom, etc., & sheet-rocked off from the other rooms; there is no need for a flue, vent or chimney with an indirect.

Most these units have a small footprint, so space is rarely a problem.
 
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Old 04-05-07, 07:48 PM
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jack, i disagree with a couple of things

the number of gallons that you count is the number of gallons in the whole boiler - the copper tubing is just a coil that passes heat heat to the domestic water as it flows through it
- what's important with the coil is how long it is and how clean the outside is

if the coil is in good shape it should be adequate for as normal sized family

the downside of that distinction is that you need to keep your boiler at say 180 in the summer just give you enough flow to heat up 120 water at perhaps 3gpm - the water has to pass through the coil submerged in the boiler to get heated, so flow can be limited, especially as the copper surfaces get encrusted over time, even worse if there is any oxygen getting in

but i totally agree with everything else

i wish they'd bring some wall hung indirects to north america - they make them that small in europe - great with a modulating condensing boiler that packs a high max BTU rating if you're tight on space
 
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Old 04-05-07, 10:53 PM
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Wink

I think if we put it all together here what has been said. Call some one . Have them clean the coil out and check the tempering valve if you have it there.
 
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Old 04-06-07, 09:53 AM
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Messing with valves

Thanks for all the input. I would love to get an indirect hot water heater put in, as from what I've read everywhere they are pretty efficient. I just can't quite bring myself to do the necessary destruction of the house to get it placed, since it can't go in the boiler room. We may remodel our upstairs bedroom in the next year, which is above the boiler room, and so when we do that it seems it would make sense to get the water heater placed in a closet up there when we do.

In the meantime, I was tinkering with the valve for the cold water supply feeding into the heating coil last night and seemed to get some better results as a result. I shut the valve partway in the hopes of slowing down the flow of cold water into the coil and it seemed to help. Does that seem like it would actually help or am I just fooling myself?

Also, there's a shutoff valve connecting the hot water line coming out of the coil to the cold water line coming in to the coil. Does anyone know what this valve does?

I'm going to take a picture of the boiler room setup when I get home tonight and post it.
 
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Old 04-06-07, 03:43 PM
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Valving

Often reducing the flow thru the coil will provide a more consistant temperature of the domestic hot water.
Just in case you were not aware, the indirect does not have to be right next to the boiler. Mine is about 25 feet away.
 
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Old 04-06-07, 07:37 PM
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It will probably be tough to get the flow controlled accurately with the inlet valve but it is a good start because you don't have to drain or disconnect anything. The reason it helps is because when the water flows more slowly through the coil, it has more time to be heated. When you close the valve too far, you will not have enough water to take a shower. The you will have to open it up a little. Don't open the one between the hot and cold. It is a failed attempt by someone who didn't understand the dynamics of water pressure and volume, to mix water temperatures and get more hot water at the fixtures. It only makes things worse.

Ken
 
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Old 04-07-07, 07:39 AM
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Here's a picture of the setup going into the coil. Sorry you have to copy and paste but I think html is turned off in the forums.

http://img297.imageshack.us/img297/7807/dscf1749pk7.jpg

The pipe on the right with the valve partly closed is the cold water feed and the pipe on the left is the hot water coming out. I've read some things on the internet about installing a flow regulator valve on the cold water supply - do you think this would help the situation?

I checked the valve connecting the cold water to the hot water (the blue knob in the picture), and it is shut. I've noticed that after I closed the supply valve partly, I'm getting warm enough water from the downstairs shower and sink and the upstairs sink, but not the upstairs shower. It still isn't hot enough considering that I've got them turned all the way to hot, but it's warm enough to take showers which is a major improvement.

I'm thinking that since the showerhead upstairs is the previous owners' while the one downstairs is one I put in, I wonder if the flow regulator on it is broken or removed. If it is pulling more than the 2.5 gpm it claims then it seems like that might be why it is running cold, while the 1.5 gpm faucets are warm enough and the 2 gpm shower head downstairs is warm enough. I'm going to test it today by my wife and I taking our showers downstairs to confirm that the shower is warm, and if that is the case, then I'll move the showerhead from downstairs to upstairs to check it before going out and buying a new showerhead.

I tried calling another plumber about the problem, and they said it sounded like a coil problem so they referred me to a place that does coil cleaning. The coil place then told me that since I have hot water pressure, it probably isn't a coil issue (I guess if the coil needed cleaning, the mineral buildup would reduce the hot water pressure?) and so I should call my oil company and have them look at the boiler. Since yesterday was Good Friday, it was pretty much a holiday here in New Jersey (which is weird to me, growing up in Florida and moving up here only last year) and I have to get them out here next week.

I was looking at the temperature guage and it reads 180 degrees on the bottom half of the guage, which I take to be the heating temperature of the domestic water portion? That dial never wavered even as I was drawing hot water from a couple different taps, so does this mean that it could be broken?
 
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Old 04-07-07, 10:22 AM
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Hot Water

The lack of heat transfer is almost certainly due to a crapped up coil either internally or externally (or both). It does not take a lot of deposited minerals to inhibit the heat transfer. Most likely, the cheapest thing to do would be to replace the coil. In many cases this can be done as a DIY project BUT there are pitfalls which can turn a simple coil replacement into a major project. Regardless of if you decide to have the existing coil cleaned, have it replaced, or replace it yourself, I suggest the installation of a good tempering valve. Obviously, an indirect is the first choice but with space limitations & the cost of an indirect, the choice has to be made by you.
 
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Old 06-02-07, 11:34 AM
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Smile Follow-up

Sorry to post a follow-up so late, but I was finally able to get my oil company out a few weeks ago and they were able to fix my problem. It turns out that the blue valve referenced to before was a crude mixing valve and the rubber portion inside of it had degraded so that cold water was just bypassing the heating coil and mixing directly with the water coming out from the coil.

Additionally, the previous home owners had apparently set a differential setting on the thermostat to reheat water only when the temperature had dropped 10 degrees from what it was set at.

These two things combined were causing our complete lack of hot water, and now we are enjoying nice hot showers.

Thanks again for everyone's help.
 
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Old 06-02-07, 01:05 PM
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Got 'er Fixed

Good deal. Glad they were able to get you fixed up with a simple & inexpensive (presumably) repair.
 
 

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