Hot water baseboard return temps exceed 20 deg differential

Hot water baseboard return temps exceed 20 deg differential

PostBy: lsayre On: Thu Jan 23, 2014 2:27 pm

My return temps exceed the ideal differential of 20 degrees for my coal boiler, just as they did in years past for my resistance boiler. The house is beiing heated just fine. Is there any concern associated with this? I have a 3 speed circulator and I can bump up the speed. Would this be of any benefit?
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (if I ever get it fixed)

Re: Hot water baseboard return temps exceed 20 deg differential

PostBy: Sting On: Thu Jan 23, 2014 3:17 pm

There is no one single reason or silver bullet to fix when return temps are too hi - or exceed the optumum

but consider why the return water is still to hot????

because it [maybe] didn't spend enough time in the radiation load to give up the energy it carries into the room

It Depends - but making the water flow faster might not be the correct step

but tryit and see - if you chose not to decide - you still have made a choice

if you want to slow the flow - try twisting a valve [just a little at a time] --- but NOT one on the suction side of the circulator
Sting
 
Other Heating: BurnHAM=NG-gas

Re: Hot water baseboard return temps exceed 20 deg differential

PostBy: Rob R. On: Thu Jan 23, 2014 3:26 pm

Unless the rooms that have radiation at the end of a loop are cold, I wouldn't worry about it. It would be simple enough to bump the circulator up one speed and see how it behaves, but that it is up to you.

Someone once told me that the delta of 20 degrees between boiler supply and return temperatures has its roots in the early days of cast iron boilers...too high of a delta stressed the boiler sections. Maybe Sting can confirm this.

Edit: I see Sting beat me to it. I read it as the return temperature is lower than expected.
Rob R.
 
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Other Heating: Dad's 1953 EFM Highboy

Visit Lehigh Anthracite

Re: Hot water baseboard return temps exceed 20 deg differential

PostBy: Sting On: Thu Jan 23, 2014 3:32 pm

ok -- maybe me bad again

lsayre wrote:My return temps exceed the ideal differential of 20 degrees


I read this as the return temp was too HI ie the work "exceed"

Larry post the temps and clear this up
Sting
 
Other Heating: BurnHAM=NG-gas

Re: Hot water baseboard return temps exceed 20 deg differential

PostBy: Lightning On: Thu Jan 23, 2014 3:39 pm

Sting, you are Rush fan?? I will choose a path that is clear, I will choose.....

:D

Nice!
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

Re: Hot water baseboard return temps exceed 20 deg differential

PostBy: Sting On: Thu Jan 23, 2014 3:41 pm

FREEWILL
Sting
 
Other Heating: BurnHAM=NG-gas

Re: Hot water baseboard return temps exceed 20 deg differential

PostBy: kstills On: Thu Jan 23, 2014 4:22 pm

Takes me an hour for the return temps to get within a 20degree window... :shock:
kstills
 
Stoker Coal Boiler: WL 110
Stove/Furnace Make: Leisure Line

Re: Hot water baseboard return temps exceed 20 deg differential

PostBy: KLook On: Thu Jan 23, 2014 4:23 pm

X2

Kevin

FREEWILL
KLook
 
Stoker Coal Boiler: Harman VF 3000
Coal Size/Type: rice, bagged, Blaschak
Stove/Furnace Make: Harman (Back In Maine)
Stove/Furnace Model: VF 3000

Re: Hot water baseboard return temps exceed 20 deg differential

PostBy: GoodProphets On: Thu Jan 23, 2014 6:29 pm

I guess X3

An hour is good, hours is normal in this house.
With these 0 degree temps, I am running all night.
But keeping temp, so I am happy!
GoodProphets
 
Stoker Coal Boiler: EFM DF520
Coal Size/Type: Anthra Rice
Other Heating: 3 Fireplaces

Re: Hot water baseboard return temps exceed 20 deg differential

PostBy: lsayre On: Thu Jan 23, 2014 6:56 pm

Sting wrote:There is no one single reason or silver bullet to fix when return temps are too hi - or exceed the optumum

but consider why the return water is still to hot????


I didn't make myself clear. When my supply is at 180 degrees, my return is less than 160 degrees. More like 150 degrees.

I guess much of this depends upon when the supply/return temperatures are taken. Eventually the zones heat up and the T-Stats are satisfied and they shut off. When should I measure the supply/return temps? Shortly after a zone valve opens and the return loop feels hot, or closer to when the zone is satisfied and about ready to shut off?
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (if I ever get it fixed)

Re: Hot water baseboard return temps exceed 20 deg differential

PostBy: Sting On: Fri Jan 24, 2014 8:22 am

Larry - in my world in these conditions - the zone pumps should be active as much as possible and off as little as possible. This is to maintain the load with no cold spots and not drafts and no on off heat cycles appearing to the occupants of the rooms -- in my case the 2 cats in the house LOL no one else home!

So that written - if you have some ambition and desire - now is a great time to experiment with temperature and flow - first in your primary loop[ if you have that ] - then starting with the longest / largest loop -- and back and forth


I would play with temperature first because -- as you have written - every degree of loop or boiler temperature you can drop - you save $$$$ circulate with lower energy bearing water but keep the boiler above condensing temperatures ---AND keep the rooms warm - you willknow when you have dropped too far in this weather and its simple to just slightly go back!!!

- your mileage may vary on condensing temperature. I say 145 some say higher some say lower some say potato I say potato -- you get it

System Balance - yes its a balance - best performed when the system is under full load as it is this time of year - once you got it -- YOU simply adjust your boiler temp {or primary loop temp} up or down [ either manually or via an automatic out door reset] in relation to the outdoor temp/weight on dwelling - and you will never have to touch the rest of the system -- this will give you will have the best possible run time cost.

if I can help specifically - please reply - I am not here afternoons and evenings -- this week I have been helping other neighbors stay warm- then of course I just have to stop and see if the girls at the bar are warm - this two drink min is getting to me - I can't count after one and some folks just have to take advantage of that - "Hay Sting you want that 2nd"

me: ummm/drool is Sky dancing next??? It Depends

Kind Regards
Sting
Sting
 
Other Heating: BurnHAM=NG-gas

Re: Hot water baseboard return temps exceed 20 deg differential

PostBy: franco b On: Fri Jan 24, 2014 12:29 pm

Sting wrote:"Hay Sting you want that 2nd"

me: ummm/drool is Sky dancing next??? It Depends

W.C. Fields said "if you can lay on the floor without hanging on, you are not drunk".
franco b
 
Hand Fed Coal Stove: V ermont Castings 2310, Franco Belge 262
Baseburners & Antiques: Glenwood Modern Oak 114
Coal Size/Type: nut and pea

Re: Hot water baseboard return temps exceed 20 deg differential

PostBy: lsayre On: Fri Jan 24, 2014 1:20 pm

When I was in Milan Italy (years ago) the bars I saw there didn't have stools. You had to stand at the bar. Makes it a lot easier to know when you've had enough.
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (if I ever get it fixed)

Re: Hot water baseboard return temps exceed 20 deg differential

PostBy: mikeandgerry On: Fri Mar 07, 2014 4:21 am

Axeman Anderson likes to stress that steel boilers are strong and resilient. While it is always advisable NOT to thermal shock your boiler, I don't think a delta t of 30degF is a problem with your steel AHS.

Most of my zone loops run a delta t of 20degF by design, but one simply has too much radiation on it (not by design, because I am a novice, and made an error!) and it always runs a delta t of 30 unless I run the boiler at 190degF.

The recommended starting temp for an Axeman using a DHW coil is 170. Anything less than 165 and my kids complain that the water gets "cold". It actually doesn't get "cold", they just notice a change in temperature and don't realize that they need to turn up the hot. (We use a proportional thermostatic mixing valve.) I prefer to leave it at 170 fall and spring and put it at 180 for the winter (this is to say the triple aquastat is: low 160/ high 180 and low 170/ high 190, diff 10degF respectively).

I never got to see the inside of a bar in Milan but I did like the few sights I did see, particularly il Duomo di Milano. I am always impressed by the fact that it is covered by statues including the tops of the spires and there are not two of them the same, even the ones 100 meters in the air. It makes my feeble engineering musings so insignificant!
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mikeandgerry
 
Stoker Coal Boiler: Axeman-Anderson Anthratube 130-M

Re: Hot water baseboard return temps exceed 20 deg differential

PostBy: LsFarm On: Mon Mar 10, 2014 11:31 pm

I'm with Rob on this. If the room with the last section of baseboard is still comfortable with 150* water providing the heat, then there is nothing wrong, and no reason to change anything..
If those rooms at the end of the loop are cool, I'd first bump up the circulator to HI, and see if there is a noticable effect. THEN if you were on the lowest setting, bump it down to the middle speed and see if it is a good compromise.

You can close off some of the baseboards in the first part of the loop, especially if those rooms are too warm.. then the heat removed from the water will be less at first, raising the end of loop temperature.

Greg L
LsFarm
 
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

Visit Lehigh Anthracite

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