Water Temperature and Pressure

[chrnits]

As part of our bathroom remodeling, we had our plumber install a Grohe Grotherm 3000 integrated valve part # 34 126. The integrated valve runs to a wall mounted showerhead and a second ceiling mounted showerhead is fed through a separate valve. We have to concerns:

1. We cannot get cold water out of the showerheads. I know the thermostat is adjustable, but our plumber insists that nothing colder than warm water will come out of the thermostatic valve. Is this true?

2. Although the water pressure from the ceiling mounted showerhead is great, the pressure from the wall mounted head is very weak. I know there is and economy adjustment setting in the volume control which our plumber insists is properly adjusted. But I have my doubts.

Any advice is greatly appreciated.

 

[Jadnashua]

There's a temperature scale on the adjustment knob...you can't get outside of the range listed on it. So, depending on the supply water temperature, you may not even be able to get as low as marked since all cold might not be colder that the marking. Don't remember what the spec sheet says...have you checked it out online? Also, was it checked and adjusted (if necessary) so that the readout and actual are within tolerance? that's part of the setup instructions.

If the showerheads are not plumbed properly, you can't get good flow from both at the same time. To get both working well generally requires a loop rather than a branch and T configuration.

 

[Sponsor]

 

[Peanut9199]

The Grohe 34 126 000 is a 1/2" thermostaic valve, at even 45 psi it will give you 7gpm and a normal shower head is 2.2 gpm.
You cannot get cold water out of this valve, your plumber is correct.
I'm not sure how you have this piped up because this valve has a built in volume control which will control only one unit.
Unless you have a diverter valve coming from the volume control i don't know how you have two units operating or do they both come on at the same time when you open the volume control?

 

[chrnits]

The two showerheads work independently of each other. I'm not sure of how they are piped, but I believe the wall mounted head is fed directly through the top feed of the thermostat and the ceiling mounted head is run through the bottom feed of the thermostat which is connected to a separate valve.

When both heads are running full out the water pressure is about the same as if only one is going. Therefore I think the water supply is adequate. My issue is with the wall mounted head which does provide a enough presure even when its the only one flowing.

I'm surprised this thermostat will not deliver cold water. Are all thermostat valves this way?

 

[Jadnashua]

Water colder than skin temperature feels cold...it will get lower than that. Most people don't want a truely cold shower. Haven't investigated enough to know exactly how all work.

 

[Peanut9199]

I spoke with Grohe because that valve is to be used with one unit or a "twin elbow" which will work with a diverter spout.
They said if your using it for second unit you will have reduced pressure and a fluctuation in the water temperature if you use both at the same time.
The reduced flow will have to be after the thermostic valve if you have no problem with water pressure on one.

Check the volume control if that is feeding the shower head with reduced flow. The volume control has a stop valve that may be partially block or the shower head itself may have a blockage.
If there is no blockage you might want to try removing the flow restrictor in the shower head.

 

[chrnits]

Thanks for the suggestions. I fixed the temperature problem by calibrating the valve properly. I was reluctant to attempt this because the Grohe instructions made it look complicated, but it really is straight forward. I now have cold water at about 21C (prior to adjustment, it was 32C).

As for the water pressure, it must be the showerhead (Grohe 28 275) since the flow or the temperature doesn't change when rain shower is turned full on (Grohe 28 373). I'm going to try swapping the showerhead with one from another bathroom and subjectively compare the flow.

 

[Jsherriff]

Grohe Calibration

I am having a hard time finding any documentation on calibrating the Grohe temperature valves. Can anyone point me to a source? Thanks.

 

[Jadnashua]

I couldn't find mine (burried somewhere), and e-mailed their tech support...they sent me the installation/maintenance doc as a PDF. Give it a try for your model.

 

[steinbierz]

Thanks for the suggestions. I fixed the temperature problem by calibrating the valve properly. I was reluctant to attempt this because the Grohe instructions made it look complicated, but it really is straight forward. I now have cold water at about 21C (prior to adjustment, it was 32C).

As for the water pressure, it must be the showerhead (Grohe 28 275) since the flow or the temperature doesn't change when rain shower is turned full on (Grohe 28 373). I'm going to try swapping the showerhead with one from another bathroom and subjectively compare the flow.

I'm curious how you got your valve adjusted. I have a 34.124 valve and my plumber friend and I could never get it adjusted right. Right now I have a max temp of 110 and a min. of 90. A slight turn of the adjustment gives me cold water (ground temp) but the max drops down to 104. I have read the instructions and reread the instructions and can't figure out what we're doing wrong. I don't know how we could have it assembled incorrectly but something isn't jiving. Thanks.

 

[williama]

As part of our bathroom remodeling, we had our plumber install a Grohe Grotherm 3000 integrated valve part # 34 126. The integrated valve runs to a wall mounted showerhead and a second ceiling mounted showerhead is fed through a separate valve. We have to concerns:

1. We cannot get cold water out of the showerheads. I know the thermostat is adjustable, but our plumber insists that nothing colder than warm water will come out of the thermostatic valve. Is this true?

2. Although the water pressure from the ceiling mounted showerhead is great, the pressure from the wall mounted head is very weak. I know there is and economy adjustment setting in the volume control which our plumber insists is properly adjusted. But I have my doubts.

Any advice is greatly appreciated.

This is a late reply but I thought that others might be interested.

I had the same experience of getting no cold water. I contacted Grohe and was advised to grind off the Stop tab on the inside of the knob (there is a red coloured plastic insert inside). I now get full cold. Others had posted it was not possible to get cold from certain Grohe mixer valves, as had two plumbers that dealt with my wife's bathroom reno. We have a nice old cast iron tub and a hot bath is great - but cold is needed to get the temperature just right - and fool around with lots of luke warm water coming from the Grohe mixer. Grohe would not do the mod due to legal concerns, but one tech there sent me instructions. It was not rocket surgery.

I do have a question for other Grohe customers - I have noticed that there is over-shoot on the temperature of the water. When one turns it to a hotter setting, the temperature goes hotter, then back again . I checked this with a thermometer and it does shoot up momentarily to almost maximum setting, then comes back right away. It does this in the other direction too, going to a colder set point it overshoots, then comes back up. Anyone else have this? It is not critical to me (thick skinned old bugger), but is somewhat annoying while in the shower and wanting a hotter setting after a minute of aclimatization. It tends to deviate from the intention of not scalding babies etc - code issue?

no. 2 of above quoted post - check for a flow restrictor and/or teflon tape injudiciously applied.

 

[GJP]

Hi williama
Was just wondering if you would be willing to post a link to / forward those instructions you got from Grohe? Would love some ice cold water coming from my shower this summer!

 

[williama]

cold

Hi williama
Was just wondering if you would be willing to post a link to / forward those instructions you got from Grohe? Would love some ice cold water coming from my shower this summer!

I will check my records - in the meantime, take the 'knob' off. inside are black and red plastic mouldings. The red one has tabs that stop rotation past the set point for hot, and for cold. It is obvious which one is the cold-stop. Remove that tab by cutting it with a knife, or grinding it away - I believe I used a Dremel tool - a file would also work.