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Central Heating

Why is my hotwater lukewarm at maximum tap flow?

Anonymous user 28/02/2024 - 3.36 PM

I just had a new combi boiler installed (Vaillant ecotec 832). This boiler has a flowrate of 12.9L/min. The boiler is in the kitchen on the ground floor. At the kitchen tap, the hotwater is hot at lower flow rates but lukewarm at its maximum flowrate (approx. 14L/min). Upstairs, at the bathroom tap, the hotwater is hot at lower flowrates (it is less hot than the kitchen hotwater) but lukewarm (cooler than the kitchen tap) at/near maximum flowrate (approx 12L/min). The radiators cannot warm the house as much as my previous system (gravity fed) and seem unable to heat the house above 22C. This issue persists even when I set the boiler to heat water to the maximum temperatures: 65C for taps; 75C for radiators. The temperature outside has mainly been 8C during this time. I live in a 3 bedroom terrace house with 6 radiators and 1 bathroom. Why does my new boiler seem incapable of sufficiently heating the hot water (taps and radiators)?

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3 Answers

T.c. Plumbing and heating

Rating: 5 out of 5

Bridgwater

Possibly just air causing the radiator issue or system requires balancing, and hot water issue at bath tap could be due to tap supply traditionally being 22 mm therefore a larger bore of pipe for hot water delivery

Answered10 April 2018

Boiler Homecare

Rating: 5 out of 5

Honiton

Surely you should be putting this question to the person who carried out the new boiler install!? It appears to me the boiler is being starved of gas. Important you get to the root cause, if it insufficient gas then you have a very serious problem. Act now!!!

Answered11 April 2018

T Services

Rating: 5 out of 5

Eastbourne

when the hot water is being used the central heating is switched off during this time, it cant do both at once like your old system did, also did they flush out the old system before installing this new boiler? these boilers are more efficient so smaller water ways and prone to blocking up. this will invalidate your warranty aswell, and if its now sludged up inside the boiler the transfer of heat within the heat exchanger will not be as efficient.

Answered12 April 2018