When a gas water heater is connected, to an oil burner, is that called an indirect? If that's correct, what's the reason for continuing to use the coil in the oil burner? It seems like a stupid idea to me. It can't be saving any money.

The woman needs a new water heater. Is there any reason why I can't eliminate the coil? Can I cap it? Any other options?

I can post a pic when she gets home from the nail salon. Her nails are more important than a stupid water heater.

 

If a gas water heater is being installed..... discontinue the use of the boiler coil.

You'll need to look into changing the boiler over to cold start so that it doesn't heat the boiler water in the summer any more.

Using the gas water heater over the oil will be a cost savings.

 

When domestic hot water is supplied from a coil in the heating boiler it is called a "tankless coil". It is the second worst method of providing domestic hot water ever devised. The absolute worst is a kettle sitting on a wood-fired kitchen range.

An "indirect" water heater is a storage tank that contains a coil, much more tubing than a tankless coil, with the coil connected to the heating boiler. This is a reasonably efficient method of providing domestic hot water.

Sometimes a storage tank is connected to a tankless coil in order to increase the intermittent flow rate of the tankless coil. It works, but has most of the downsides of the tankless coil in addition to taking up more space.

Having an entirely separate water heater is, in my opinion, the better method because it means that your heating boiler may fail yet you will still have hot water. If you are installing a separate heater to replace a tankless coil you do not need to cap off the tankless coil but you do (obviously) need to transfer the cold water supply and the hot water outlet piping to the new heater.

Some people argue that the tankless coil should not be capped because IF it has water it could develop a hydraulic lock causing the internal pressure to skyrocket. OR, they will argue that an internal coil leak will cause the same problem. In my opinion these people are simply not looking at the situation in a logical manner. I personally would cap the abandoned coil connections.

 

I have to agree with that 100%.

I had a customer that had a gas water heater installed. The boiler coil was left uncapped and developed a leak. I needn't tell you where the water went.

 

Forget about it. The tank isn't leaking. It's a shower problem.

 

When most of the water is drained out of a water heating coil being decommissioned, capping off the coil will not result in large pressure changes and differences inside the coil as the oil burner unit or other boiler cycles on and off.

 

Update: I went to the house to try to find the leak. I couldn't reproduce it but I was able to determine that it wasn't the boiler or the hot water heater. Since the floor is sloped, there is only one way that the water could have flowed.

The house is a split level. There is a straight vertical PVC drain pipe from the upstairs bath with a clean out at the bottom. Apparently the leak came from there. As I said, I couldn't make it happen again. We ran the shower, the tub, the sink with & without the boiler running. I noticed a vent on the roof which may or may not have something to do with it.

I also saw what needs to be done to correct the indirect problem. It looks simple enough to reroute the feed to the hot water heater & to cap the coil.

 

Exactly....that is correct.

 

One more thing. There is what I believe to be an aquastat(s) mounted on the coil. I haven't opened it so I don't know if that covers the coil temp & the baseboard water temp. What has to be done in there?