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Brand new Combi-fed Thermostatic Shower not Staying hot

Postby zeeman88 » Thu Sep 12, 2019 11:37 am

Hi Folks

Apologies if this has already been covered elsewhere but I am new to this forum.

I have recently installed a new new bathroom in my house so everything is brand new. I have a thermostatic mixer bar shower and I have a combi boiler system. When I went to take a shower last night, first one since installing it, it ran at the desired temp for a while then went cold, the boiler then fires up again for a few seconds and the water becomes warm again briefly. This process continues and therefore I cannot get a shower without it going cold. I have removed the flow restrictor at the shower head.

I have listed what troubleshooting I have done so far below;

1. I tried the hot water taps and all work fine, I can run a bath and no issue with the hot water.

2. I cracked a hot water tap in the bathroom while running the shower, the boiler constantly ran and the temp was good, did this for about 10 mins.

3. Removed the shower head and tried the shower only, the boiler starts and stops but not as frequently and the temp of the shower stays consistent. This seems like the correct working scenario?

From the above findings I assume the problem is with the shower head restricting the flow of hot water? Could it be as simple as that, if so do different shower heads have different flow rates? I cannot find any info on the flow rate of the shower I have in the manual etc.

Thanks in advance :)
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