Do you have enough solar to go off grid in winter?

[zƬesla]

@BGbreeder The product you linked to looks like something for water tanks, not boilers.

Let's say we get a heat pump water heater. Does it go inline with the boiler and indirect hot water storage tank (SuperStor) and if so where, or would a bypass for one or both need to be installed? If we bypass the boiler altogether, it will sit cold for most of the year; can't imagine that's good and dependable when it may be most needed (deep winter)?

 

[nwdiver]

@BGbreeder The product you linked to looks like something for water tanks, not boilers.

Let's say we get a heat pump water heater. Does it go inline with the boiler and indirect hot water storage tank (SuperStor) and if so where, or would a bypass for one or both need to be installed? If we bypass the boiler altogether, it will sit cold for most of the year; can't imagine that's good and dependable when it may be most needed (deep winter)?

The 'heat geek' YouTube channel has a lot of good info on heat pumps for boilers. I would expect there to be a lot if innovation in this sector over then next few years as the UK is pushing to replace their NG boilers with heat pumps.

Heat Geek

 

[CrazyRabbit]

More pollution.

Letting wood decay naturally release as much carbon dioxide as burning it.

 

[getakey]

Letting wood decay naturally release as much carbon dioxide as burning it.

yeah, but one happens in a week or so and the other over hundred years

 

[BGbreeder]

The 'heat geek' YouTube channel has a lot of good info on heat pumps for boilers. I would expect there to be a lot if innovation in this sector over then next few years as the UK is pushing to replace their NG boilers with heat pumps.

Heat Geek

@BGbreeder The product you linked to looks like something for water tanks, not boilers.

Let's say we get a heat pump water heater. Does it go inline with the boiler and indirect hot water storage tank (SuperStor) and if so where, or would a bypass for one or both need to be installed? If we bypass the boiler altogether, it will sit cold for most of the year; can't imagine that's good and dependable when it may be most needed (deep winter)?

Yes, they are generally used in hot water heaters. Electrolytic anodes are used in both. After hard water, the main enemy of boilers is oxygen as it is the element in the corrosion of metals.

Generally, you would add your preheater heat pump water heater ahead of the superstor, with perhaps a recirculating pump moving cooler water from the superstor back to the heat pump water heater. If it were me, I would cut the the oil fired indirect heating system out, but it might be easier to leave it in place depending on the plumbing.

Can you describe your system in some more detail? Am I understanding that your oil fired boiler provides baseboard backup heat during the winter, and that hot water is used to heat your potable water? The oil fired home boilers that I am familiar with aren't usually open to the air, so the only source of oxygen is either decomposition within the boiler and pipes, and/or air leaks. If you are concerned about corrosion in your radiators and pipes, circulating the water periodically will help keep the water and additives mixed, and the anti-corrosion additives dispersed in your system. Generally, they include sodium nitrite (oxygen scavenger), borates to regulate pH, and silicates to reduce scaling, e.g.

Boiler Water Corrosion Inhibitor - Stop Boiler Corrosion

ChemWorld 2338D is a Boiler Water Corrosion Inhibitor in 5 and 55 gallon containers form $139.99 with free Delivery. Stocked in Atlanta, Georgia; Taylor, Michigan; and Salt Lake City, Utah.Michigan, Georgia, and Utah.

www.chemworld.com

(Disclaimer: I have never used their products, that is merely an example.) You need to keep testing the nitrite levels to know when to add more. They make test strips like, pool water testing.

Have you thought of using a diesel generator to drive a heat pump water heater for the base board heating, and using the waste heat from the diesel to boost the heat pump? It would be more efficient than many boilers, but I don't know the specifics of yours...

All the best,

BG

 

[zƬesla]

The boiler handles both the forced hot water baseboard heating and potable hot water. Years ago we installed a 60-gallon SuperStor indirect hot water storage tank. So the boiler heats and the SuperStor maintains potable. There is a total of 7 heating zones including 2 generally unused in the basement. A few years ago we started using our Mr Slim mini-splits for heat in winter (and quickly installed solar after seeing the electric bill). We live in northern NH, where temps can get below 0F. Our low last night was around 14F. The zone thermostats are usually set a few degrees below the heat pumps to automatically pick up any major dips.

The impression I was left with from the tech after our last boiler cleaning a month or so ago is that not using the boiler would result in reduced gas expansion increasing the possibility of the insides rusting out more quickly (or some such?), and that the occasional calls for potable hot water was sufficient to prevent this.

Seems like installing a heat pump water heater would require a boiler bypass or as you say removing the boiler altogether. As this would take out the heat fallback, would prefer if there is some way of having all 3 inline (boiler, HP WH, SuperStor) or with an auto-bypass.

I'd rather avoid generators, but may consider them as a fallback. However, not sure I can entirely rely on a heat pump system given potential for low temps and outages.

We used to have anti-freeze in the pipes but drained that as it was causing corrosion. Will check out the inhibitor in more detail.

 

[DrGriz]

yeah, but one happens in a week or so and the other over hundred years

I got to watch one of the biggest fires in the state this year burn up an amazing swath of forest this summer right from my living room window. It's still smoking after a foot of snow. Who knows, but maybe enough to heat a thousand homes for 40 years. (Wild-ass guess there). I have always felt that, at least in our community/region, wood burning for heat probably reduces fuel for big wildfires and pays for itself in "carbon credits". Better it burns in my efficient woodstove than out in the forest.

As my solar installer says, "it's going to burn anyway."

YMMV

 

[wwu123]

The boiler handles both the forced hot water baseboard heating and potable hot water. Years ago we installed a 60-gallon SuperStor indirect hot water storage tank. So the boiler heats and the SuperStor maintains potable. There is a total of 7 heating zones including 2 generally unused in the basement. A few years ago we started using our Mr Slim mini-splits for heat in winter (and quickly installed solar after seeing the electric bill). We live in northern NH, where temps can get below 0F. Our low last night was around 14F. The zone thermostats are usually set a few degrees below the heat pumps to automatically pick up any major dips.

The impression I was left with from the tech after our last boiler cleaning a month or so ago is that not using the boiler would result in reduced gas expansion increasing the possibility of the insides rusting out more quickly (or some such?), and that the occasional calls for potable hot water was sufficient to prevent this.

Seems like installing a heat pump water heater would require a boiler bypass or as you say removing the boiler altogether. As this would take out the heat fallback, would prefer if there is some way of having all 3 inline (boiler, HP WH, SuperStor) or with an auto-bypass.

I'd rather avoid generators, but may consider them as a fallback. However, not sure I can entirely rely on a heat pump system given potential for low temps and outages.

We used to have anti-freeze in the pipes but drained that as it was causing corrosion. Will check out the inhibitor in more detail.

What about just having a heat pump water heater wired in-line as a pre-heater for the SuperStor? The hybrid system then replaces some or most of the boiler fuel cost for heating potable water with electric heat pump. Just using some round (but inaccurate) numbers as an example, if your cold supply temp is 60 deg, and you keep your potable hot water at 120 deg:

If you use the heat pump to pre-heat from 60-90, rather than most people using it as their complete heating from 60-120, you're using it even more efficiently (as the heating portion from 90-120 is more inefficient), and you minimize the standby losses since its tank is only at 90. Then that 90 deg water feeds SuperStor, which I assume the passive heat exchange transfer has the same 100% efficiency between 60 to 120 deg, but since it's only heating from 90-120, instead of 60-120, you've cut the operating fuel in half (the boiler is burning fuel incrementally to make up for the heat loss. And you can change that pre-heat setpoint from 90 to 100 or higher if the efficiency of the heat pump and cost of electricity is more economical than the price of boiler fuel (oil?). I'm ignoring what I assume are huge standby losses from keeping a boiler running, but since you're running it from home heating, we can look only at the incremental fuel used for potable hot water heating.

But while the heat pump is very efficient at extracting heat from the ambient air, if it's using the surrounding room air then that room is getting colder. Then the cold room is going to absorb heat from somewhere. If it's being replenished from say basement walls and the surrounding earth, no problem. If the boiler is in the same room, it may just absorb more heat from the boiler walls, forcing the boiler to burn more fuel, and you've just lost all your savings....

 

[zƬesla]

@wwu123 not sure I follow how to have the HP-WH inline for just partial heating. The general flow for potable is:

cold in -- boiler -- SuperStor -- faucet

And for heating:

cold in -- boiler -- baseboard

I think what you're suggesting is having the HPWH between the boiler and SuperStor? However, I don't think efficiency-wise lowering the boiler temp makes sense.

To your last point, the HPWH would likely be installed near the boiler and SuperStor.

Here's a pic:

 

[BGbreeder]

The boiler handles both the forced hot water baseboard heating and potable hot water. Years ago we installed a 60-gallon SuperStor indirect hot water storage tank. So the boiler heats and the SuperStor maintains potable. There is a total of 7 heating zones including 2 generally unused in the basement. A few years ago we started using our Mr Slim mini-splits for heat in winter (and quickly installed solar after seeing the electric bill). We live in northern NH, where temps can get below 0F. Our low last night was around 14F. The zone thermostats are usually set a few degrees below the heat pumps to automatically pick up any major dips.

The impression I was left with from the tech after our last boiler cleaning a month or so ago is that not using the boiler would result in reduced gas expansion increasing the possibility of the insides rusting out more quickly (or some such?), and that the occasional calls for potable hot water was sufficient to prevent this.

Seems like installing a heat pump water heater would require a boiler bypass or as you say removing the boiler altogether. As this would take out the heat fallback, would prefer if there is some way of having all 3 inline (boiler, HP WH, SuperStor) or with an auto-bypass.

I'd rather avoid generators, but may consider them as a fallback. However, not sure I can entirely rely on a heat pump system given potential for low temps and outages.

We used to have anti-freeze in the pipes but drained that as it was causing corrosion. Will check out the inhibitor in more detail.

What occasional calls for domestic hot water heating does for your boiler is to circulate some water through the boiler (your backup heating loops are valved out). That buys you some mixing of the water, but anti-corrosion additives will do more. If your technician insists that you need it cycling, you could use a recirculating pump on a timer, but I may be missing something about your boiler. A hot water boiler shouldn't normally have an air/water interface in it. If you were getting increased corrosion due to antifreeze, I suspect that there was something wrong with the antifreeze/water chemistry. That shouldn't happen. Given where you live, not having antifreeze is a nonzero risk, but that's your call. Having lived through some major storms and outages, I wouldn't do it, even with Powerwalls and solar.

What I was endeavoring to suggest is that you cut the boiler out of the domestic hot water system, and just use the heat pump to heat the water. Since the Superstor is passive, you would need some sort of circulation pump to pull cold(er) water out of the Superstor to be (re)heated.

As @wwu123 pointed out above, your heat pump water heater will be "stealing" heat from wherever it is located. If it can source heat from an unheated basement, that is great, but if not, you are "robbing Peter to pay Paul".

Going full throttle, there are heat pumps designed to heat water, and baseboard heating with that water is nearly ideal. (In floor heating would be ideal.) It all comes down to money and what your goals are. I have lived in homes with several different variations on water / steam heating. I get the historic reasons for them, but other than in floor heating, I am not a fan as they are often a corrosion nightmare, and someone needs to understand water chemistry to keep the system from rusting into leaks and floods. Plus, many of the ones that I lived with were a long way from quiet, but that's a personal foible for sure. To me, a big upside to oil fired heating is that you can store enormous amounts of energy in your supply tank. (Which is also a fire risk, especially if it is in the basement rather than in a double wall tank outside, but that's neither here nor there...)

All the best,

BG

 

[RKCRLR]

yeah, but one happens in a week or so and the other over hundred years

I'd really like to see a study of how many greenhouse gases stay sequestered in a forest over a 200 year cycle vs responsible management of a forest that includes harvesting for energy vs where the energy would otherwise come from. I've looked and haven't found one. A lot of methane is released as wood decays. And if forests around me are left unattended they will eventually burn releasing CO2.

I'm in a high wildfire risk area and firesafe rules say that I'm supposed to remove any dead trees to the property lines. Eventually, all trees will die. What am I supposed to do with them if I don't cut them up and use them as firewood?

 

[BGbreeder]

@wwu123 not sure I follow how to have the HP-WH inline for just partial heating. The general flow for potable is:

cold in -- boiler -- SuperStor -- faucet

And for heating:

cold in -- boiler -- baseboard

I think what you're suggesting is having the HPWH between the boiler and SuperStor? However, I don't think efficiency-wise lowering the boiler temp makes sense.

To your last point, the HPWH would likely be installed near the boiler and SuperStor.

Here's a pic:

View attachment 874869

Great photo, and very informative!

OK, that sure looks like a corrosion nightmare to me. You have copper and black iron piping mixed, with no dielectric fittings in a couple of places as far as I can tell. On the one hand I would like to ask how much of the black iron pipe leaving the basement could be removed/abandoned in favor of copper or PEX/Al/PEX piping? On the other hand, this is what you have. I would get anti-corrosion additives in the system, and I would not change anything else until it rusts out. At that point, I would go for a plan B, with an all copper system, including the boiler/heat pump system depending on which way you go.

If you have a choice of boiler technicians, I might have some other company look at it and see what they say. I am not a boiler professional.

Given what you have, I would be inclined to sort out the antifreeze and corrosion inhibitors, and keep using it as is until it fails.

All the best,

BG

 

[getakey]

I'd really like to see a study of how many greenhouse gases stay sequestered in a forest over a 200 year cycle vs responsible management of a forest that includes harvesting for energy vs where the energy would otherwise come from. I've looked and haven't found one. A lot of methane is released as wood decays. And if forests around me are left unattended they will eventually burn releasing CO2.

I'm in a high wildfire risk area and firesafe rules say that I'm supposed to remove any dead trees to the property lines. Eventually, all trees will die. What am I supposed to do with them if I don't cut them up and use them as firewood?

Use them for firewood. I have a woodstove too. My only point was that comparing burning wood to decaying wood is not apples to apples.

 

[RKCRLR]

Use them for firewood. I have a woodstove too. My only point was that comparing burning wood to decaying wood is not apples to apples.

I agree but I would really like to see a comprehensive evaluation that considers where replacement energy would come from vs letting a forest die and replenish naturally without making use of the resources. And that's assuming it doesn't go up in a wildfire.

 

[zƬesla]

@BGbreeder we used to have antifreeze but was finding it causing corrosion so had it taken out as we live here full-time. In addition to the front circulator, there are two in back for an addition built just before we bought the house. They used PEX for that and it's all discolored. Don't care so much about that, but I think they used the wrong kind that may have caused oxidation?

I've reached out to 3-4 companies and they seem to know their niche and that's it. Doing some kind of hybrid system seems beyond them and we're rural enough that it's tricky getting some "city-folk" to come out.

In the same room as the boiler there's also the washer/dryer. Would like to get a heat-pump dryer when the current one goes. Keep hearing mixed recommendations on whether it would be an issue with the boiler which has a damper in the pipe coming out the top.
Would having both a heat-pump dryer and water heater would be an issue?

 

[BGbreeder]

I'd really like to see a study of how many greenhouse gases stay sequestered in a forest over a 200 year cycle vs responsible management of a forest that includes harvesting for energy vs where the energy would otherwise come from. I've looked and haven't found one. A lot of methane is released as wood decays. And if forests around me are left unattended they will eventually burn releasing CO2.

I'm in a high wildfire risk area and firesafe rules say that I'm supposed to remove any dead trees to the property lines. Eventually, all trees will die. What am I supposed to do with them if I don't cut them up and use them as firewood?

I did pretty extensive research on this a while back. Long story short; if you are in an area that favors soil accumulation, then some (small) fraction of the carbon gets sequestered into the soil. (e.g. Think Ohio) If you live in some location with little to no topsoil accumulation (e.g. almost all of California, the Amazon basin) then, yes, the dead tree gets 100% returned to the atmosphere or ocean.

Given where you live, I think that collecting downed wood and cutting the occasional tree is preferable to using any other form of energy.

All the best,

BG

 

[BGbreeder]

@BGbreeder we used to have antifreeze but was finding it causing corrosion so had it taken out as we live here full-time. In addition to the front circulator, there are two in back for an addition built just before we bought the house. They used PEX for that and it's all discolored. Don't care so much about that, but I think they used the wrong kind that may have caused oxidation?

I've reached out to 3-4 companies and they seem to know their niche and that's it. Doing some kind of hybrid system seems beyond them and we're rural enough that it's tricky getting some "city-folk" to come out.

In the same room as the boiler there's also the washer/dryer. Would like to get a heat-pump dryer when the current one goes. Keep hearing mixed recommendations on whether it would be an issue with the boiler which has a damper in the pipe coming out the top.
Would having both a heat-pump dryer and water heater would be an issue?

I understand living in a rural area and not having lots of choices. That's why I think I would leave it as is until it fails, but at a minimum trying to get some anti-corrosion additives in the system.

As long as you have the boiler there, a heat pump dryer should be fine. Whether there is enough "waste" heat to run a heat pump water heater and a heat pump dryer after the boiler goes...I don't know. How big is the basement? Much as I would prefer a heat pump dryer, when I ran the ROI on a heat pump dryer, I couldn't make it work, even for our relatively expensive power. The ROI was beyond any reasonable lifetime for the dryer. What is the (suppose) issue with the damper on the boiler and a heat pump dryer?

There is PEX and PEX/Al/PEX tubing. The former is used for domestic potable water and is oxygen permeable and it usually comes in clear (translucen), blue, and red for hot water. PEX/Al/PEX tubing is not very oxygen permeable and is used for heating, and usually comes in orange, but other colors are made. If you have a heating system with just PEX, you would have a problem with significant amounts of oxygen getting into your system, causing corrosion and rust. Beyond repiping the plain PEX as PEX/Al/PEX tubing, I have no experience in dealing with that and I don't know how to cure it.

All the best,

BG

 

[zƬesla]

That's kind of where I'm at unless I see some potential return. With a quote of $10k+ for a new boiler (installed), and ours still in decent shape if not the most efficient after 30+ years, I rather wait given what seems to be rapid changes in heating tech.

The HP dryer issue as I understood it had something to do with the performance of the damper. Again, people around here seem to have limited knowledge and willing to spout things they may have heard somewhere but with no solid backing. Even the energy auditors we had come by have been less than stellar and we had to kick one out before the work was done.

Basement with boiler and dryer is ~544sqft with adjoining open door to ~550sqft (addition mentioned above). So roughly 1100sqft. Plus another connecting (closed door) basement of ~750sqft.

We have Eversource which doubled its rate a couple of months ago. Figured any efficiency in the dryer would help. And my family would harp on me less when I tell them to wait and do laundry when the sun is out

 

[wwu123]

@wwu123 not sure I follow how to have the HP-WH inline for just partial heating. The general flow for potable is:

cold in -- boiler -- SuperStor -- faucet

And for heating:

cold in -- boiler -- baseboard

I think what you're suggesting is having the HPWH between the boiler and SuperStor? However, I don't think efficiency-wise lowering the boiler temp makes sense.

To your last point, the HPWH would likely be installed near the boiler and SuperStor.

Mind you, I've never seen a boiler before so just going by basic engineering principles and filling in with your picture, but I believe the flow for heating is a closed-loop system, non-potable, that you sometimes have put anti-freeze in but don't frequently add more water, so basically:

cold in (non-potable) -- boiler -- baseboard -- cold in (back to the boiler)

and there's another closed-loop run to the SuperStor heat exchanger. These are the two black-insulated pipes going in and out the front of your SuperStor:

cold in (non-potable) -- boiler -- SuperStor heat exchanger -- cold in (back to the boiler)


In the back of the SuperStor not visible in the pic, facing the wall , I believe should be a cold-supply line coming in the bottom, and a hot-water line coming out the top going to the faucets. This is the actual potable water flow

cold supply in -- SuperStor water tank -- faucet

and I was suggesting using the HP water heater as a pre-heater

cold supply in -- HP WH -- SuperStor water tank -- faucet

Given the HP water heater would be in the same boiler room, and thinking more about whether it would be efficient or not: my guess is that since it's a large basement with a lot of wall and floor exposure to the earth, if your typical basement temp is about the same as your cold water supply, then your basement is not being overheated by waste heat coming off your boiler. Then the HP would primarily be stealing heat from the basement walls/floor/air, and not just making your boiler work harder. OTOH, if your basement is warm like 70 deg because all this heat is coming off the boiler and pipes, that heat is just being wasted and sucking back into the walls anyways, so maybe better to have the HP water heater steal it in that case too....

 

[BGbreeder]

@wwu123 Don't forget heat flowing from the warm floor above...

@zƬesla heat pump dryers are closed loop; that is the air gets recirculated inside, so I can't imagine why someone thinks a damper on a boiler is an issue. Depending on your laundry needs, one heat pump dryer may be problematic just from the 120-180 minute cycle times. I.e. They work well for one or two loads of laundry a day, and work best with a front loading HE washer on high speed spin to spin out as much water as possible.

All the best,

BG