How To Make Current System More Efficient

VelvetFoot

Hi.  I'll be installing a pellet boiler in parallel with an existing boiler in a 10 year old 2000 ft2 colonial with two baseboard zones driven by a Taco 007 circ pump each pumped towards the return header.  A new edition will a 120 gallon buffer tank, with 11 gal of that used by a stainless coil for dhw. The existing expansion tank is on the supply header. 



How can I make things more efficient?  Should I convert the pumps to zone valves and put a variable speed pump right after a new air separator (Spirovent?) and expansion tank off of the buffer tank so  that it 'pumps away' from the heat source, which will now be the buffer tank?  Is pumping away that desireable?  It's not like the high end zone valves are that big a money saver over pumps.  I can see for energy savings, but reliability?  How about two ECM pumps to replace the existing pumps, continuing to pump to the return?



I can't realistically tear up floors and ceiling to add pipe,panel radiators, etc but would like to do somewhat of a makeover for more efficiency, heating and electrically, but not neglecting reliability.



Thanks for any suggestions.





 

Snowmelt

Out door reset

Get out door reset, zone sentry valves and bumble pump.

VelvetFoot

Outdoor reset?

How would the odr control the temp. outlet of the buffer tank, since that will be in essence the "boiler"?    I'll need 140f or so in the buffer tank, min, for dhw. Would there be some mixing going on?  I was hoping maybe replacement delta t ecm pumps would be able to vary zone flow for efficiency.

Snowmelt

O.d.r.

It won't, I miss read actually read to quick this pellet stove is it the same thing ad an outdoor fernace/ boiler. The delta t pump will work for comfort level.

Last time I did this I used a flat plate heat exchanger , the customer used 0 oil , so I don't understand what your doing with the buffer tank

VelvetFoot

Buffer Tank

This is an indoor pellet boiler that modulates down to 30%  It does not come with outdoor reset.  I plan to continue using my wood stove insert some, and will heat upstairs zone with pellet boiler at times.  Plus, want to limit starts and stops of pellet boiler because it takes like 10 minutes to get things going. 

Zman

Details

Do you have hot water baseboard?

What model are the boilers?

Have you purchased the buffer tank? Does it have 4 ports so it can be used as a hydrolic separator?



Depending on the answers to the above questions, I think the ideal plan would be to have the 2 boilers piped in parallel on one side of the buffer tank/ separator. The heat manifolds would come off the other side.



You will save electrical circulator energy by going with zone valves and ECM.circ. You need to pump away from the expansion tank .



Outdoor reset will not help much with efficiency as both boilers are non condensing. It may help with comfort.



The controls are pretty simple. Keep the buffer tank at a certain temp using a 2 boiler controller with an adjustable differential to assure long cycle times.



Carl

CMadatMe

Simple

reset the system not the equipment.. Use a 3-way modulating mixing valve. Does the pellet boiler have a 0-10VDC input in the control? If so, you can use a Tekmar control for the ODR of the boiler..

VelvetFoot

Details

Do you have hot water baseboard?

Yes, see first post.



What model are the boilers?

Burnham V8, Windhager BioWin 150



Have you purchased the buffer tank?

Not yet.

Does it have 4 ports so it can be used as a hydrolic separator?

No.  It has 2 for boiler and 2 for dhw.

http://woodboilers.com/products/heat-storage-systems/energy-tank.html

SWEI

Read up

http://www.caleffi.com/sites/default/files/coll_attach_file/idronics_10.pdf before you start buying parts.

VelvetFoot

Thanks for the link

Thanks for the link.  It was a nice overview.

PLUMMER

ODR is not more efficient???

What does a condensing boiler have to do with ODR?

The boilers will do one thing feed the buffer, then the buffer will feed the load. ODR by taco iValve or similar will control the supply temp to the load. This will allow him to make use of a wider temp range. No need for 180 degree supply temps with spring temps.



The buffer will also improve cycle times and add to efficiency. Since it only turns down to 30% this means it will probably be doing 30-45kbtu. If there are any zones smaller than that, a buffer will surely help to not waste and have less on/off cycles.

heatpro02920

Efficiency...

If it were me I would not add a tank to your system, does your burnham have a tankless coil?



I would personally pipe it so your burnham is used as the buffer tank, I would use its tankless for DHW {if it doesnt have one add it}, I would pipe the system primary secondary and I would not use zone valves, I would install a bumble bee set for delta t on each zone {rebates are available in some places}....



I did a system this way {with a coal boiler, much better than pellets if this is an option}, I will try to find the drawing in a minute...



I use tanks in my systems as a last resort, a modern water tank is just about guaranteed to cause you grief at some point in time, so to add one just to use as a buffer, no thanks, I would find a better way to do it...

heatpro02920

heres an idea

This is a similar system I did, but for what you want to do I would probably do it a little different...

heatpro02920

I changed it a little

I changed the drawing from the other job, I would do yours similar to this, so the zones are using the closely spaced tees and the boilers are on the loop like the picture shows. Then you can wire the system pump to run all the time or on an aquastat, I would use delta t pumps on your zones and then size the system pump according to what you need, a bumble bee would be fine, I wouldn't set it up delta t, but play with the speeds and settings until you find the best way to run it...

You can wire it so the boiler is kept hot no matter what and you will have plenty of hot water with the tankless...



Use your burnham as a buffer and if you don't want the stand by losses from the pellet boiler when you are running the burnham you can install a bypass and some iso valves... Not too hard to figure out, I am sure there are a ton of options for you, but if you can save the expense of a tank and not have it in your system then do yourself a favor and do so... I install a lot of equipment and by far the most failures I see before warranty and after is tanks, for some reason we can not make a good tank that will just last 15+ years, indirects, storage, directs, no matter what kind of tank I have seen them fail far sooner than they should...

And for no reason, I wish a company would come out with a thick high quality ss tank that would last as long as a ci boiler, a nice 30-40 year life expectancy tank, heck I would be happy with one that would consistently last 20, they cost almost as much as a boiler after all...