Upgrade boiler?

[EatenByLimestone]

When does it make sense to upgrade a boiler that is still working well?

My boiler is way oversized. It was oversized when I inherited the house, and I've worked on this house to the point it's no longer the same house. I've upgraded windows and insulation, air sealed and then air sealed some more. I'm currently foaming the basement walls as I feel that's where a good portion of my heat exits. The boiler is used to heat water and heat the house.

Any ideas on when or if it should be upgraded? I don't burn as much at the house as I used to since I switched the oil burner out for gas. The boiler is used to heat water in addition to the house.

 

[maple1]

What exactly is it?

My old wood/oil boiler was working as well as the day I bought it new, basically. But it was an inefficient little piggy when new too. So I hit my breaking point dealing with piles of coals, frequent firings, lost sleep, and sketchy trips up on the roof for chimney cleaning.

I guess my input would be - personal preferences?

Depending on exactly what you have, might be different things you can do - like heating your DHW with something else & shutting the boiler down in the off-heating seasons.

 

[EatenByLimestone]

It's a WM gold. I converted it from oil to gas in 09 or 10. 85% efficient or so from the factory. Maybe a bit more so.

Hot water is a Bedarus 30g unit.

I'm interested in other ideas for heating water. Electricity is .25 a kwh or so.

 

[maple1]

When I replaced our boiler, I also put in a new conventional 80 gallon electric hot water heater.

Should have done that years ago.

Heating DHW with a boiler isn't very efficient, no matter the fuel source. Stand by losses up the flu are big. Plus it adds a cooling load to your house in the summer (adds heat when it is already hot).

Our DHW costs now during the summer are around $20-25/mo, of 0.18/kwh electricity. Heating it with the oil boiler before was very close to a gallon of oil per day.

I assume you mean natural gas? That's usually a hard one to beat, cost per BTU wise. Maybe an on-demand NG DHW heater? Not familiar with those...

 

[EatenByLimestone]

When I replaced our boiler, I also put in a new conventional 80 gallon electric hot water heater.

Should have done that years ago.

Heating DHW with a boiler isn't very efficient, no matter the fuel source. Stand by losses up the flu are big. Plus it adds a cooling load to your house in the summer (adds heat when it is already hot).

Our DHW costs now during the summer are around $20-25/mo, of 0.18/kwh electricity. Heating it with the oil boiler before was very close to a gallon of oil per day.

I assume you mean natural gas? That's usually a hard one to beat, cost per BTU wise. Maybe an on-demand NG DHW heater? Not familiar with those...

That might be a good option. I'll have to look into them.

 

[EatenByLimestone]

Anybody have any experience with them?

 

[Circus]

A separate water heater is a must, no matter what flavor. A boiler usually operates at over 180f. with all the associated losses. Using it to heat water to 120F is super wasteful except in winter. If you use a lot of hot water, use gas. If not, electric because the standby loss is low.

 

[DBoon]

Roughly speaking, if your boiler is 30 years old and you replace it with a newer reasonably efficient new boiler, then you can expect a 25% improvement in overall efficiency - that is what I achieved with a replacement oil boiler. I too would replace an oil or gas-fired HW tank with a heat pump water heater, even at .25/kWh.

 

[velvetfoot]

Wow, natural gas: fantastic.
Natural gas units are very efficient nowadays. No chimney required. PVC pipes right out the side.
You have a Buderus 30 gallon indirect dhw tank. That could stay. The new boiler would heat it more efficiently, I believe.
You could buy a properly sized mod/con gas boiler. I'm not sure if you'd use the condensing aspect, but it would modulate to building load.
I bet you could get a rebate from Grid. You could probably get one for your central A/C as well, lol.

My niece recently replaced her oil boiler when gas came into her area. She has a Super Store indirect dhw tank. She wound up keeping the Super Store and getting a Bosch boiler. She had thought about getting a different Bosch boiler that also had instant dhw built in, but decided against it. I think there can be issues with whole house instant dhw.

 

[woodgeek]

Get a new, EF=3.5 HPWH and shut down the boiler in the warm weather.

Personally, if you have a good location for it (near the boiler) I'd just run the HPWH 12 mos a year.