Update on the taco bumblebee update

[davem3261]

I'm using a bumble bee on my boiler. I made it reverse acting by putting a resistor instead of a sensor on the return. I'm using the sensor on the supply. I run it on delta t. Took awhile to find the right setting. It runs at 11w most of the time and kicks up to 41w when the boiler goes over 190. Then it drops back down to 11w at 185.

 

[kuribo]

Sounds interesting! delta T of what? What is the pump supplying?

 

[BoiledOver]

I'm using a bumble bee on my boiler. I made it reverse acting by putting a resistor instead of a sensor on the return. I'm using the sensor on the supply. I run it on delta t. Took awhile to find the right setting. It runs at 11w most of the time and kicks up to 41w when the boiler goes over 190. Then it drops back down to 11w at 185.

Wow, sounds like a slick way to go. Could you share more detailed info on how you set this up? What specs on the resistor? Do you have boiler protection besides this pump? Danfoss or other such thermostatic valve or loading unit?

 

[davem3261]

The pump is on the boiler loop. I used a 2200 ohm 1/4 watt resistor from radio shack. Makes the pump think there is a constant 155 return temp. I set the delta t to 35. I have an aquastat and a zone valve set at 150 for return protection

 

[davem3261]

Picture

 

[BoiledOver]

Thank you for the follow up.

 

[maple1]

225,000Btu/hr = 500 Q dT

dT= 90

Q= 5gpm

Don't see why?

There is a boiler loop with another pump that does about 16-18gpm with a 30F dT through the boiler. It's like injection mixing. The large dT means I can pump a lot less water....

On my zone supply side I will use 2 Viridian pumps as I have two supply runs, each with 2 zones and want the redundancy....


Whoops, see Mr. Dudley has already explained....

But, what I am seeing, is that through the boiler, your return should be min 140. So if supply gets to 190, that would be dt50. But as the burn progresses, your DT will narrow as storage warms. Towards end of burn, it could approach 10.

 

[kuribo]

The return water from storage is always 100F. You take less flow out of the boiler loop as the boiler output falls to keep the output of the boiler at 190F. The boiler input is kept at 150 or 160 or whatever by varying the flow through the boiler loop.

 

[kuribo]

The pump is on the boiler loop. I used a 2200 ohm 1/4 watt resistor from radio shack. Makes the pump think there is a constant 155 return temp. I set the delta t to 35. I have an aquastat and a zone valve set at 150 for return protection

So what exactly are you controlling the pump to do?

 

[maple1]

I completely overlooked the two-pump plan, oops. What do you have for a boiler loop (bypass?) pump? I was thinking this would be one pump to move all water through boiler - a thermostatic valve setup.

 

[kuribo]

Maybe this will help:

 

[kuribo]

I talked to Taco today and have good news and bad news: the good news is the pump should work fine in reverse or setpoint cool mode out of its published range by inserting a resistor in line with the sensor. The bad news is these pumps do not shut off when the set point is reached but rather continue to operate at the lowest speed.

I don't understand how the pump could control to a set point if it never shuts off- if it never shuts off, wouldn't it have to have a very loose control band in order to meet the set point?

So, to use these pumps as I have proposed would entail an aquastat or other such switch to turn them off completely...seems if you have to use an aquastat to turn them on and off you could just use a regular pump instead....Hmmmmm......

To correct my earlier post, I spoke today with Doug Bird, the product manager at Taco for the Viridian pumps. He told me that actually the Viridian vt2218 in set point mode will stay powered but basically go into a sleep mode when the set point is reached, rather than go into a low speed mode.

Thus, they should work fine for my application and I plan to buy several as soon as they become available.

He also said they are hoping to roll out these pumps nationwide by September.

 

[TCaldwell]

Let's hope they actually do, unlike the bumble bee!