BOSCH T9800SE 160K BTU having Heating Problem Water Flow Rate shows 0.3gpm No Heating

tester22

Hi there, I need help from BOSCH Experience exports those who have knowledge about this BOSCH. We have BOSCH T9800SE 160K BTU Machine, and we have Heating problem from last full Winter 2022-2023. When Heating ON it will blow Cold Air, but some time Hot Air Blow shortly (to get this Heating work I need to leave TAP or SHOWER continuously open, during this time gpm shows like 0.7gpm etc).
When we check Water Flow Rate shows on Machine 0.3gpm or 0.4gpm while Heating ON (when there is no TAP or SHOWER ON).

We have RED ZONE DVS 600 Furnace, so Fix every thing on Furnace Side like.
-Replace New Heat Pump.
-Replace all Pipes in Loop.
-Install Drain Tap & Shut Off Valve on HWR (Hot Water return).
-Replace Air Bleeding Pin on Coil.
-Descale BOSCH Tankless Water Heater.
-Clean Water filter, Air Filter inside BOSCH Machine.
-we inspect Check Valve, Flow Control, In-Line Check Valve all clear.
-We did Air Bound Purge Air out from system & Loop etc.
-we check Domestic Water Pressure 65psi & Expansion Tank Pressure 70psi, all good.
-we increase Temp on Hot water Tank from 122 up to 140 degree.

We did many more practical Testing, After doing above this all, still Water Flow Rate shows 0.3gpm or 0.4gpm.

And there is no problem at all on Furnace side, only the problem need to Fix on BOSCH Machine. So I want to know, how to increase Water Flow Rate up to 0.9gpm at least to get Heating Work.

We spend 8 over months for doing above all Testing one by one, finally notice problem need to fix in BOSCH Machine.

Please help us to fix, we have good Knowledgeable about BOSCH Machine.

Any Task please give us, we will do practical Test and Post in this Thread by Photos etc.

tester22

tester22

I am new, Thanks to Admin Staff my Thread is visible.

GGross

Where is the space heating pump

dko

OP's prior discussions
https://hvac-talk.com/vbb/threads/2249229-Red-Zone-DVS-600-Air-Handler-Furnace-connect-with-Tankless-Hot-Ware-Heater-having-Hea
https://www.diychatroom.com/threads/red-zone-dvs-600-air-handler-furnace-connect-with-tankless-hot-ware-heater-having-heating-problem.748455/

He has a pump in the AH

tester22

Hi there, Heat Pump inside the Furnace. New Pump already installed, and from Furnace side all good. Only the problem need to fix on BOSCH Machine to increase gpm.

This BOSCH Machine stopping/preventing Water Flow any water coming from Loop, that is why Loop is not Activating.

Need to do some Collaboration, may be Bypass etc. if you know any thing about this BOSCH Machine, please help me I will do Testing and post my result promptly. Here is New Pump Installed Photos for your kind consideration.

tester22

dko

tester22

in this direction Check Valve Installed. And yes Check Valve installed right Direction, please have a look in Photo.

GGross

Has this ever worked properly?

In my experience the pressure drop through a tankless water heater's heat exchanger is greater than most people would think, likely requiring a larger pump than one might normally select to get the proper flow through the heat exchanger. I would imagine that the pump inside the fan coil is not adequate to pump through the tankless unit, let alone the fan coil and tankless unit at the same time which is why you are only getting 0.3 GPM when the pump is on.

tester22

Where as in my Neighborhood all having the same system installed, in their home Heating is perfectly working fine with the same heat Pump. I am posting few photos for your kind consideration. And they are getting 1.6gpm when Heat is ON.

GGross

can you clarify the direction that it is indicated on the brass check valve as @dko pointed out? It should be stamped into the check valve showing flow direction

dko

Nevermind

tester22

There is an arrow on check valve, in this exact direction we installed that Check Valve. Before that Check valve is very close to BOSCH Tank.

After seeing Neighbor Home then install in the middle.

tester22

My New Heat Pump installed Perfectly fine, here is the result for your kind consideration.

dko

I think you should only post current photos, another check magically appeared.



does this check also have an arrow facing right towards the right wall? if so, it's wrong

tester22

Please have a look this is the New photos, just now I took it, and on Check Valve it is showing Water Flow Direction, and yes Check valve Installed is right direction 100% confirm. I am attaching 2 Photos by showing direction of Water Flow,.

dko

talking about this one above the bosch, if it's still there

tester22

No that is the old PEX Pipes & Old Check Valve place all removed and installed new PEX line, so the same Check Valve goes and sit in the middle in the latest photo, the same way installed in Neighbor Homes.

For doing proper inspection, we Remove and Re-Installed back all back again all New there.

dko

Do this and let us know results.
Caution if operating correctly, hot water will be coming out the hose bibb.




Anywhere on the Inlet[supply] pipe ever get hot? Does the water coming out of the red handle hose bibb ever get hot?



If it does get hot:
Pump is not circulating, or not circulating enough.
Does the GPM on the Bosch change whatsoever when you change the speeds from I II III on the pump? Is the pump actually running?


But question asked before: has this system worked prior to you repiping and replacing parts?
Please answer this question

pecmsg

tester22 said:

My New Heat Pump installed Perfectly fine, here is the result for your kind consideration.

If it was installed “Perfectly Fine” you wouldn’t be here asking the question’s!

you never said what was the supply / return pressures at the same time. 

tester22

During this Testing, we did below
BOSCH Machine - ON,
Heat Pump - OFF
On HWS: Drain Tap - OFF, Shut OFF Valve - ON
On HWR: Drain Tap - ON, Bottom Shut Off Valve - ON, Top Shut Off Valve -OFF

Hose connect to Drain Tap on HWR, shows 1.5gmp
During this Testing HWS pipes very hot. And Water collect in Bucket is very Hot.

pecmsg

Not what I asked for. 

Supply and return pressures at the same time!

tester22

Domestic Water Pressure & HWS Water Pressure

dko

He meant put the gauges on the HWS drain tap and HWR drain tap at the same time. 

SuperTech

I believe he only has one gauge 

SuperTech

I believe the important questions have already been asked. 

Do the pipes get warm at all when the heat is calling?

Any change of flow indicated when the circulator speed is changed? 

Do you have any way of checking voltage and amperage draw at the circulator motor?

pecmsg

SuperTech said:

I believe he only has one gauge 

2 gauges are needed

All we’re getting is Standing Pressures!

tester22

Here it is HWR Press


ure Test

I Don't have 2 Gauges

pecmsg

From your last post. 

Both gauges show 65#’s so that means NO FLOW!

SuperTech

I have been following this problem on HVAC-TALK.COM and now here. This has been frustrating to follow. I'm pretty sure the right professional tech would be able to figure this out relatively easily with the right tools. I wouldn't have put up with this for months. @tester22 have you tried the find a contractor tool on this website? Unless you are determined to DIY this a pro would be your best option. 

SuperTech

Was the flow sensor replaced when the parts cannon was fired at this?

tester22

I am confuse, which part you call it as FLOW SENSOR, are you talking about that part in BOSCH Machine, if that never replace any thing in BOSCH Machine.

And How that Flow Sensor look like in BOSCH Machine. Please let me know from 1st post photos.

tester22

Minimum I paid to 5 HVAC Techs, they just took my Money, and no body identified any problems, they not even did any thing, they just took my Money and gone.

After that I my self start Testing, and I did many many Testing on this, every thing clear from Furnace side, only the thing need to Fix in BOSCH Machine.
When we call to BOSCH Staff, they said this is the problem of Furnace side in COIL & LOOP, need to clear all to Activate Loop for Heating. So I did from Scratch all all all from last over 8 months.

And BOSCH tech don't want to talk with Home Owner, we learn about their BOSCH machine, so when I call to any HVAC Tech, I have to Teach him when they don't understand to BOSCH Staff.

And we know AUTO Tuning & Manually adjust GAS & AIR Pressure etc. This time need to do some thing New Testing in BOSCH Tank.

pecmsg

No manufacture will talk with the end user. Too much liability. 

Sorry you found bad techs unfortunately that’s the way things are. 

Keep looking, we’re out there!

SuperTech

I'm not an export with the BOSCH MACHINE, but there's got to be a flow sensor that is telling the BOSCH MACHINE what the flow rate is. I'm sure the wiring diagram would indicate this. I'm just guessing, but it could be faulty. I would make sure the circulator works too. Do you have an electric multimeter?

tester22

yes I am expecting this, there is some thing in BOSCH Machine may be that Flow Sensor is here some
where

And I have this Multimeter.

tester22

When Old Pump sitting there, when we did Bucket Test, the Water Flow is very Slow, as you can see in Photos. Now compare to New Pump, Water Flow is Very Fast & good in New Pump.

SuperTech

Do you see any difference in flow readings on the BOSCH machine when you change the speed on the circulator/pump. If your flow into the bucket changes with lower/higher speeds than it should change on your BOSCH machines display screen.  I have seen those flow sensors fail on other boilers/machines. 

tester22

OLD PUMP: When there is Old Pump at that time Water Flow shows 0.3gpm or 0.4gpm. Where as Old Pump Water pressure is very Low, when Heating is ON. Still shows 0.3gpm or 0.4gpm.
High, Medium, Low - no difference in Flow Rate.

NEW PUMP: When there is New Pump at this time Water Flow shows same 0.3gpm or 0.4gpm. Where as New Pump Water pressure is very very good, when Heating is ON. Still shows 0.3gpm or 0.4gpm.
High, Medium, Low - no difference in Flow Rate. But currently on High.


In both Testing there is no difference in gpm at all, that is why finally I suspect in BOSCH machine need to do some Testing there.

tester22

PULL OUT CARTRIDGE FROM FLOW CONTROL TEST:
When we pull out Cartridge from Flow Control, after this Water flowing with the speed of 65psi in Loop. Then we Run heating, after this still this BOSCH Machine shows Water Flow 0.3gpm or 0.4gpm. Where as this is very very high speed of water flowing. But BOSCH Machine is preventing Water Flow, so there is Water flow shows 0.3gpm or 0.4gpm.

Please have a look in photos from scratch FLOW CONTROL TEST
















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