Question:
I think if you check you’ll find it’s actually ‘ahead’ of the coil in the boiler, not after where a ‘holding’ tank would be. It’s called a tempering tank, it warms the water to room temp or at least warmer than coming out of the ground so the coil can raise the temp easier/faster.
No, it’s definitely after the hot water, not before. You can see the cold water line going in (and feel the pipe) to the coil and the tank is on the outlet from the coil. Between the outlet and the modified tank, there are two valves. First a shut off, second a blowoff, then a run of pipe up to the top of the tank. You should be able to use the classified ads to find a used heater for maybe $50. Your boiler shouldn’t have any trouble heating domestic water in the winter time. You may find you have a coil full of water hardness scale, or, the tank is actually after the coil and your hot water is cooling down in it before you use the hot water.
Both these are reasons I want to change this tank – either could be true. I also wonder if the water is stratifying in the tank rather than mixing, leaving cooler water to be drawn off. The coil is not the original – there’s no way of knowing for sure but it appears to be about thirty years old (the boiler is from 1924 or so). It’s old enough and the water is hard enough for minerals to be a problem. I would guess that the age of the boiler would make it too expensive to repair/replace. I toyed with the idea of having it descaled, but, again, this thing is soo old……. You sure there isn’t a by-pass valve between the cold feed and hot water lines that’s leaking or partially open as a mixing valve? Follow the water line from your pressure tank/meter and make sure you know the direction of flow and where the water goes. Boiler water and the domestic water doesn’t mix, they’re separate.
I know about the boiler and domestic water. I even explained it to the home inspector who took pictures of "Moby Boiler" for his collection. Not a lot of houses with oil heat in this part of NJ anymore, and he’d never done one with this old a boiler. I haven’t been able to determine if there is a bypass. I don’t see one anywhere – which means there could be one in some odd place that I’ve missed. If things were right with the coil and boiler there is no need for the ‘holding’ tank and your type setup is probably the best there is with a new boiler. Especially if your heat runs from Sept to May.
Does that mean that these systems are similar to an on-demand type in function? As far as heat is concerned, three different plumbers looked at the boiler and after some laughter about the age (I mean, this thing has doors on it for converting it to hand-stoked coal if we ever get the urge!), the general thought was that it was in good repair and could last another seventy years with care. It’s certainly a cheap source of heat compared with gas – it costs approx. $45 a month to heat the house in season (and less once we install a set-back thermostat). Our heating season is from October to April, btw, in Northern NJ. And we do plan on staying with oil, even if we do replace "Moby" in a few years for efficiency – I think the estimated efficiency on it has to be in the 60% range…..not good. -=epm<=- In matters of truth and justice, there is no difference between large and small problems, for issues concerning the treatment of people are all the same. – Albert Einstein
Response:
– Hide quoted text — Show quoted text – It sounds like an expansion tank, not a holding tank. If a holding tank, what does it hold? Expansion tank holds air until system heats up to compensate for system pressure. Hard to say, I can’t see your tank from here. Replace all pressure relief valves and think about living with leaks. Whatever… It’s clearly a holding tank for the hot water – it comes off the "tankless" hot water boiler part of the furnace, not the steam boiler, and is connected to a mixing valve and the cold water line. In theory, heated water flows upward into the holding tank from the boiler, and exits on demand, mixing with the cold water at the mixing valve. Reality would seem that there is a small reserve of heated water that makes it into the tank, but a gas hot water heater tank can’t be the same as a tank designed for the oil boiler. And we don’t seem to have a hell of a lot of hot water. Or am I missing something?
I’ve seen many boilers and expansion tanks but can’t ever remember an expansion tank on the domestic coil side, only the boiler side. Is there a drain valve on the tank? If so drain it so it doesn’t hold as much water, and do it about once a month. Adjust (closing) the valve between the cold and hot and you should be able to scald yourselves! I adjusted one for a customer the other day that was scalding them. Hold the hot line while hot is running somewhere and when it gets just hot enough you have to let go stop. It should be very close to right when it gets to the fixtures and you shouldn’t have to use much cold water to cool it. Gary – Hide quoted text — Show quoted text – -=epm<=- In matters of truth and justice, there is no difference between large and small problems, for issues concerning the treatment of people are all the same. – Albert Einstein
Response:
We have an ancient oil boiler (with a relatively new burner) that makes both steam for heat and the domestic hot water. The previous owner took a gas hot water heater and modified it to act as a holding tank for the hot water from the boiler. This makeshift tank is vintage 1978 and needs to be replaced – there is visible corrosion on the top inlets that is making me very, very nervous. Anyone have an idea of the cost of replacing a holding tank? Is it normal to have a holding tank on one of these systems? I understand the point of having the boiler make the hot water, but it seems to be giving us insufficient hot water in the heating season when the thermostat seems to keep the hot water portion of the boiler from making enough water to meet demands for showering and laundry, etc. Since we are planning on replacing the boiler in the next few years, the question really is whether the cost of replacing the holding tank and the benefits to the existing system are greater or lesser than the costs of adding a gas hot water heater and closing off the existing part of the boiler. Any suggestions would be appreciated. -=epm<=- In matters of truth and justice, there is no difference between large and small problems, for issues concerning the treatment of people are all the same. – Albert Einstein
Response:
- Hide quoted text — Show quoted text – We have an ancient oil boiler (with a relatively new burner) that makes both steam for heat and the domestic hot water. The previous owner took a gas hot water heater and modified it to act as a holding tank for the hot water from the boiler. This makeshift tank is vintage 1978 and needs to be replaced – there is visible corrosion on the top inlets that is making me very, very nervous. Anyone have an idea of the cost of replacing a holding tank? Is it normal to have a holding tank on one of these systems? I understand the point of having the boiler make the hot water, but it seems to be giving us insufficient hot water in the heating season when the thermostat seems to keep the hot water portion of the boiler from making enough water to meet demands for showering and laundry, etc. Since we are planning on replacing the boiler in the next few years, the question really is whether the cost of replacing the holding tank and the benefits to the existing system are greater or lesser than the costs of adding a gas hot water heater and closing off the existing part of the boiler. Any suggestions would be appreciated.
It sounds like an expansion tank, not a holding tank. If a holding tank, what does it hold? Expansion tank holds air until system heats up to compensate for system pressure. Hard to say, I can’t see your tank from here. Replace all pressure relief valves and think about living with leaks. Whatever…
Response:
It sounds like an expansion tank, not a holding tank. If a holding tank, what does it hold? Expansion tank holds air until system heats up to compensate for system pressure. Hard to say, I can’t see your tank from here. Replace all pressure relief valves and think about living with leaks. Whatever…
It’s clearly a holding tank for the hot water – it comes off the "tankless" hot water boiler part of the furnace, not the steam boiler, and is connected to a mixing valve and the cold water line. In theory, heated water flows upward into the holding tank from the boiler, and exits on demand, mixing with the cold water at the mixing valve. Reality would seem that there is a small reserve of heated water that makes it into the tank, but a gas hot water heater tank can’t be the same as a tank designed for the oil boiler. And we don’t seem to have a hell of a lot of hot water. Or am I missing something? -=epm<=- In matters of truth and justice, there is no difference between large and small problems, for issues concerning the treatment of people are all the same. – Albert Einstein
Response:
We have an ancient oil boiler (with a relatively new burner) that makes both steam for heat and the domestic hot water. The previous owner took a gas hot water heater and modified it to act as a holding tank for the hot water from the boiler. This makeshift tank is vintage 1978 and needs to be replaced – there is visible corrosion on the top inlets that is making me very, very nervous.
I think if you check you’ll find it’s actually ‘ahead’ of the coil in the boiler, not after where a ‘holding’ tank would be. It’s called a tempering tank, it warms the water to room temp or at least warmer than coming out of the ground so the coil can raise the temp easier/faster. Anyone have an idea of the cost of replacing a holding tank? Is it normal to have a holding tank on one of these systems? I understand the point of having the boiler make the hot water, but it seems to be giving us insufficient hot water in the heating season when the thermostat seems to keep the hot water portion of the boiler from making enough water to meet demands for showering and laundry, etc.
You should be able to use the classified ads to find a used heater for maybe $50. Your boiler shouldn’t have any trouble heating domestic water in the winter time. You may find you have a coil full of water hardness scale, or, the tank is actually after the coil and your hot water is cooling down in it before you use the hot water. You sure there isn’t a by-pass valve between the cold feed and hot water lines that’s leaking or partially open as a mixing valve? Follow the water line from your pressure tank/meter and make sure you know the direction of flow and where the water goes. Boiler water and the domestic water doesn’t mix, they’re separate. Since we are planning on replacing the boiler in the next few years, the question really is whether the cost of replacing the holding tank and the benefits to the existing system are greater or lesser than the costs of adding a gas hot water heater and closing off the existing part of the boiler.
If things were right with the coil and boiler there is no need for the ‘holding’ tank and your type setup is probably the best there is with a new boiler. Especially if your heat runs from Sept to May. Gary – Hide quoted text — Show quoted text – Any suggestions would be appreciated. -=epm<=- In matters of truth and justice, there is no difference between large and small problems, for issues concerning the treatment of people are all the same. – Albert Einstein
Response: