New Combi Vaillant EcoPro 28 - slow Hot Tap bath only

[springer101]

Hi

I wonder if anyone is able to offer me some advice here please. I had a new Combi fitted yesterday. On completion the plumber showed me the appropriates (I was out all day having left them to it). He showed me the kitchen/bathroom sink hot tap which was marvellous in comparison to previous (old gravity fed system), he pointed to the bath as we were walking out of the bathroom and said "those aren't great taps really" - my 10 year old pointing downward taps in the bath! I didnt think anything of it at the time but on running a bath today, the hot tap in the bath only is innnn-crediblyyyyy slow! I thought mmh I wonder if thats what he meant by not great taps - thinking my way towards new ones if that were ever possible. I then proceeded to add cold water to the bath at the same time as hot...and the hot tap water just dribbled away to near nothing?!. I thought i would seek your valued opinions on here before giving the plumber a call on Monday...is this 'normal' or is something not right here? This tap was without doubt faster pre-combi and adding cold water then didnt make a jot of difference to its flow.

(just in case your wondering - hot flow is much faster than pre-combi in kitchen and bathroom sink and cold water has always been amazingly fast)

Thank you in advance, all advice much appreciated..

 

[thereisawizza]

Might be old bath taps, these actually have a 3/4" bore unlike the new "european" style taps. Got a pic of the tap?

 

[SimonG]

Combi boiler syndrome. 22 full bore versus low hot water flow from the combi.

 

[springer101]

Here's a pic of the taps,

 

[SimonG]

Nothing wrong with taps. On the old system your hot water was driven by the cold water tank in loft and your cold was probably mains. Therefore two seperate systems. Now with the combi your hot water and cold water taps are fed by the same mains water. On the gravity system the pipes feeding the bath will have been 22mm or 3/4" and would run at full bore.
The cold to the combi is only 15mm and will have a maximum temperature lift for a set flow of water. Hence when running the bath you need to run it slower. If you get it right you shouldnt need to add cold water.

 

[oz-plumber]

Nothing wrong with taps. If you get it right you shouldnt need to add cold water.

And get a hobby while you are filling the bath.
Dial the boiler into the maximum temperature setting for domestic hot water, and by the time you have filled the bath, you should have a slightly warmer bath water temperature than body temperature.
Combi boilers have their limits, and a hot bath exceeds that limit.
It's not that they can't produce the hot water, it's with the flow rate and temperature rise and the volume of water needed to fill the bath, also, the amount of heat the bath will itself will take from the hot water when filling the bath.

Bath's and combi boilers don't really get along with each other.

 

[jtsplumbing]

Not seen those style taps for years, thought they had all been replaced, you may just have a problem with the tap washer, what about getting the plumber back that fitted the boiler.

 

[GQuigley67]

And get a hobby while you are filling the bath.
Dial the boiler into the maximum temperature setting for domestic hot water, and by the time you have filled the bath, you should have a slightly warmer bath water temperature than body temperature.
Combi boilers have their limits, and a hot bath exceeds that limit.
It's not that they can't produce the hot water, it's with the flow rate and temperature rise and the volume of water needed to fill the bath, also, the amount of heat the bath will itself will take from the hot water when filling the bath.

Bath's and combi boilers don't really get along with each other.

Disagree my bath is fine off my combi. The Op is talking about the flow of water not the temperature. Could be a blockage in the tap, tap issue not boiler issue.

 

[SimonG]

Disagree my bath is fine off my combi. The Op is talking about the flow of water not the temperature. Could be a blockage in the tap, tap issue not boiler issue.

Piped in 15 or 22 to bath.

 

[jtsplumbing]

Piped in 15 or 22 to bath.

Old style Globe taps will be 3/4" (22mm)

 

[springer101]

This is the set up to upstairs bedroom then along to bathroom next door to it - middle verticle pipes - hot to left, cold to right, they are 15mm, put in about 30 years ago with original central heating

 

[SimonG]

Bet thats 15 cold up and 15 hot down. Where was hot water cylinder?

 

[GQuigley67]

Piped in 15 or 22 to bath.

22mm.

 

[SimonG]

22mm.

Does the combi have a flow restrictor?

 

[Millsy 82]

How long does it take to fill a litre bottle and what boiler is it?

 

[GQuigley67]

Does the combi have a flow restrictor?

Most combis do

 

[SimonG]

Oil ones don't. Now fit a valve on the bath hot water feed.

 

[GQuigley67]

Don't deal with oil so can't comment on them ☺