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12-26-2013, 12:52 PM
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95 posts, read 382,724 times
Reputation: 109
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This is the first time I have ever had a gas furnace and a gas tankless water heater. I like the water heater BUT if my heater is on then I can't get hot water. The display pad of the water heater says it is not getting enough gas (roughly). The water heater is for a small house and I have no idea about the furnace. What could be causing this problem? None of the guys I have out to look at it have any idea. They have never heard of the brand of water heater (Paloma) and they say the pipes are large enough.
Does the amount of gas flow get reduced as things use it? Could it be that the gas runs to the heater first then it runs out of enough for the water heater? The only thing I can relate it to is cable the is being split with splicers if anyone remembers those.
I have not heard anything bad about the brand of water heater but they keep recommending a locally known brand.
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12-26-2013, 01:12 PM
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Location: Mount Laurel
4,187 posts, read 11,286,440 times
Reputation: 3509
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Quote:
Originally Posted by HappyHitchhiker
This is the first time I have ever had a gas furnace and a gas tankless water heater. I like the water heater BUT if my heater is on then I can't get hot water. The display pad of the water heater says it is not getting enough gas (roughly). The water heater is for a small house and I have no idea about the furnace. What could be causing this problem? None of the guys I have out to look at it have any idea. They have never heard of the brand of water heater (Paloma) and they say the pipes are large enough.
Does the amount of gas flow get reduced as things use it? Could it be that the gas runs to the heater first then it runs out of enough for the water heater? The only thing I can relate it to is cable the is being split with splicers if anyone remembers those.
I have not heard anything bad about the brand of water heater but they keep recommending a locally known brand.
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Have they check to see if it's properly vented? How is the tankless being vent? The obvious reason may be the lack of gas supply but these tankless has electronic to monitor the venting. If not propertly vented, it will not operate. |
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12-26-2013, 01:20 PM
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95 posts, read 382,724 times
Reputation: 109
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Quote:
Originally Posted by sj08054
Have they check to see if it's properly vented? How is the tankless being vent? The obvious reason may be the lack of gas supply but these tankless has electronic to monitor the venting. If not propertly vented, it will not operate.
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It vents outside. If venting was the problem then why would it just start acting up now that its winter and we are running the heater? |
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12-26-2013, 01:32 PM
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Location: Mount Laurel
4,187 posts, read 11,286,440 times
Reputation: 3509
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Quote:
Originally Posted by HappyHitchhiker
It vents outside. If venting was the problem then why would it just start acting up now that its winter and we are running the heater?
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I was asking whether it share the vent with your gas boiler? If the connnection is wrong, you will get backdraft, hence not allowing your water heater to work. When the gas boiler is not running, no backdraft.
Just a hunch if the two units are sharing the same vent.
Do you have a co2 detector around the unit?
Another similiar related issue is the amount of combustion air available. Are the tankless and heater in the same enclosed room? Some utilites room are wall off but it they are too small, you need to have vent for additional air.
Last edited by sj08054; 12-26-2013 at 01:43 PM..
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12-26-2013, 02:29 PM
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95 posts, read 382,724 times
Reputation: 109
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Quote:
Originally Posted by sj08054
I was asking whether it share the vent with your gas boiler? If the connnection is wrong, you will get backdraft, hence not allowing your water heater to work. When the gas boiler is not running, no backdraft.
Just a hunch if the two units are sharing the same vent.
Do you have a co2 detector around the unit?
Another similiar related issue is the amount of combustion air available. Are the tankless and heater in the same enclosed room? Some utilites room are wall off but it they are too small, you need to have vent for additional air.
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The furnace is in the crawl space under the house (fairly common around here from what I hear) and the water heater is next to the kitchen with the washer and dryer. We have a co2 detector in that room. I don't think there is a vent for the crawl space. I don't know much about it really, we just bought the place this summer and the house was built in the 50's. |
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12-26-2013, 04:21 PM
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12,347 posts, read 18,506,498 times
Reputation: 19460
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Yes, the supply lines are too small or something is wrong with the supply from the utility. Tankless water heaters require more volume of gas than a standard water heater although they use less volume overall to heat the same water. The installer should have done a proper supply calculation to make sure there was enough gas to maintain the tankless water heater while other gas appliances were also in use.
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12-26-2013, 04:32 PM
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Location: South Park, San Diego
6,086 posts, read 10,026,027 times
Reputation: 12336
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In our area tankless water heaters require a 3/4" gas supply line and many areas (older, I presume) have only a 1/2" line requiring an expensive upgrade depending on his long the line has to be. So I'm not sure if that was checked or if that's the case with you.
I'm in the middle of debating whether or not I'm going to go that route as my existing regular water heater is 15 years old (yikes). My furnace is just a small old gravity unit (no blower) in the cellar so I bet it doesn't actually use that much gas though. And, honestly, we rarely use a furnace out this way anyhow.
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12-26-2013, 04:45 PM
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Location: Chesterfield, VA
1,222 posts, read 4,965,751 times
Reputation: 549
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About three years ago we had natural gas run to the house. There was a supply line down the street, but the original owner did not have a line run to the house. Anyway, one of the things the gas company asked was how many BTUs we would be running because they wanted to make sure the line was big enough. Initially it was just a tankless Rinnai and gas logs, but also told them hoping to add a gas cooktop and furnace at some point. The private installers also asked, since of course they installed the line under the house. Then about a year ago we added the heat pump with gas backup and a gas cooktop. We were right at the max capacity for the line size, but in talking with the gas representative, we figured it would be very rare that all four appliances were run at the same time. So you may want to call the gas company and ask about the size of the line from the street to the house.
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12-26-2013, 05:26 PM
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359 posts, read 1,047,763 times
Reputation: 256
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call your gas co. its ,a gas meter to small, or gas pressure problem , my bet small meter. just an old gas man. good luck
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12-27-2013, 05:44 PM
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Location: Jamestown, NY
7,841 posts, read 8,683,422 times
Reputation: 13779
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Wow, am I glad that I was reading this forum as I didn't know about this. Thanks for the invaluable info, folks! I have a HE gas furnace and an older, standard gas water heater that I am considering replacing with a tankless, so I'll have to be sure to check the size of my gas lines before making my decision! Since my house was built about 1925, it likely has a smaller gas line.
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