Recirculation Line for Bosch Singular 5200 Combi

cloudd

How should a DHW recirculation line loop (supply/return) be plumbed into a Bosch Singular 5200 Combi

The Bosch Singular 5200 has an internal circulation pump for DHW. It only has a cold water inlet and a DHW supply outlet.

Is a check valve required and if so where?

A diagram would be great please.

Thanks

Big Ed_4

Here is one that I found . The small storage is interesting . A hot water recirculation line piping loop needs to be insulated . The internal pump is used to move the boiler water. Not for this..

dko

The Bosch 5200 combi does not have a built-in pump for DHW. The built-in pump is the boiler pump.

You will need to install an external pump for DHW.

cloudd

I spoke with Bosch customer service and either I misunderstood the purpose of the internal pump or perhaps the lady I spoke with misunderstood what I was asking.

So what exactly is the purpose of the stated “Built-in boiler circulator pump”? What is its job?


What are some options for DHW external circulation pumps?

fenkel

The built in "pump" is designed to work with a primary/ secondary heating supply loop, This Pump does NOT work to move DHW. It moves makeup water to heat exchanger, the heat exchanger takes cold water and heats it for DHW.

yellowdog

bosch should be able to provide you the proper piping diagram of how they want a recirc tied in.

hot_rod

Do you have a dedicated hot water recirc line, return line as shown in the drawings?

It doesn't take much of a circulator to flow a residential DHW loop. All the pump brands have specific recirc pumps for DHW.

If you don't have a recirc line, some systems use a valve under the remote fixture to recirc thru the cold line.


A small 2-1/2 or 6 gallon electric tank inline reduces the "cold sandwich" lag time, where the burner takes time to fie up.


Two examples:

cloudd

I have a dedicated DHW recirculation line (return line)


Bosch told me that they don’t recommend using a recirculation pump with this combi because when it is running it take will priority over the space heating side and cause problems on the space heating side probably. No heat while it is running.

With that being said is this not usually the case with residential combi’s?



Space is tight in the basement but money is not endless…

Option:
A system that has a hot button to activate the recirculation pump manually. The only one that I found is the Grundfos 15-55 HWR-D with multiple Bluetooth remote hot buttons. Seems very expensive probably because this pumps power is maybe overkill? Are there other options?


Before I installed the Bosch combi I had a 60gallon hot water tank at the opposite side of the house. I had to wait at least 1-1/2+ minutes (I never timed it) for hot water to get to the shower. Now it take 2-1/2 to 3 minutes. I’m not sure a small tank would solve the problem.

GGross

"With that being said is this not usually the case with residential combi’s?"

This is the case with other residential combi boilers yes, and also for most typical boiler/tank setups as they are generally put on a DHW priority (at least they are around me)

as for the pump, that grundfos is a nice setup, but yeah it is more pump than you need. You can get a less expensive grundfos recirc pump, set it to run constant, and then plug it into one of those mechanical timers that plug in your wall socket. Set the correct run times on the mechanical timer. Grundfos also has another package option that is good if you do not have a dedicated recirc line, that comes with the crossover valve, pump, and a timer

I would confirm with them which one you are receiving, this looks like the old part number that had the mechanical timer on it ( these seem to last) supply house has the new part number with the digital timer listed as discontinued, so not sure what is going on there.

https://www.supplyhouse.com/Grundfos-595916-UP15-10SU7P-TLC-Comfort-Hot-Water-Recirculation-Pump-3-4-NPT-115-V

hot_rod

cloudd said:

I have a dedicated DHW recirculation line (return line)


Bosch told me that they don’t recommend using a recirculation pump with this combi because when it is running it take will priority over the space heating side and cause problems on the space heating side probably. No heat while it is running.

With that being said is this not usually the case with residential combi’s?



Space is tight in the basement but money is not endless…

Option:
A system that has a hot button to activate the recirculation pump manually. The only one that I found is the Grundfos 15-55 HWR-D with multiple Bluetooth remote hot buttons. Seems very expensive probably because this pumps power is maybe overkill? Are there other options?


Before I installed the Bosch combi I had a 60gallon hot water tank at the opposite side of the house. I had to wait at least 1-1/2+ minutes (I never timed it) for hot water to get to the shower. Now it take 2-1/2 to 3 minutes. I’m not sure a small tank would solve the problem.

Us all the piping insulated? That makes a big difference on how often the boiler would need yo run to keep the lines warm. The line only needs to be kept to 120 at the last fixture, not the entire line all the way back

cloudd

No it’s not insulated. There wasn’t enough room to easily insulate it. Plus with the recirculation line it’s like 120ft. So I get my options are:

cheaper pump with a timer for the mornings

or

A more expensive pump with a remote for manual recirculation activation.

hot_rod

If you go with a basic pump and timer, you can also add a temperature sensor at the pump return. This turns off the pump once it senses the piping is warm
The piping is all copper?

cloudd

The DHW line and return are 3/4” PEX.

Seems like there is room in the market for a lower powered circulation pump with bluetooth remotes for manual activation pump activation.

GGross

Could you use a wifi enabled power plug to turn on and off remotely? I have not used one of these personally but it says you can set a schedule for on/off, and cycle power remotely. I think there are other smart plugs available as well

https://www.homedepot.com/p/Defiant-15-Amp-120-Volt-Smart-Wi-Fi-Bluetooth-Plug-with-1-Outlet-Powered-by-Hubspace-HPPA11AWB/315636834?source=shoppingads&locale=en-US&&mtc=SHOPPING-BF-OTH-GGL-NA-NA-NA-NA-NA-SMART-NA-NA-NA-NA-NBR-NA-NA-NA-SMART_SHP_HubSpace&cm_mmc=SHOPPING-BF-OTH-GGL-NA-NA-NA-NA-NA-SMART-NA-NA-NA-NA-NBR-NA-NA-NA-SMART_SHP_HubSpace-71700000100514683-58700008035333131-92700073069493829&gclid=CjwKCAjwx_eiBhBGEiwA15gLN1ez5-CFg5--hmOL8XS-DTK2Kv2eOUgO6Qbd8pu2EK526DQji0uryBoC3KQQAvD_BwE&gclsrc=aw.ds

hot_rod

Check the brand and type if pex, depending on the CL chlorine rating category on how often you can run chlorinated water. Temperature and velocity restrictions
Don’t over pump the loop!

Big Ed_4

Do you need it ? Sprawling ranch yes...