wigeon jim Posted January 18, 2020 Report Share Posted January 18, 2020 Hi, any heating engineers on here now what is wrong with my Baxi boiler, heating side is fine but the hot water is not nearly as hot as if used to be, it's only a few years old and was serviced last July but since then the hot water has been getting cooler, anyone know what's up,. Jim. Quote Link to comment Share on other sites More sharing options...
Lord Geordie Posted January 18, 2020 Report Share Posted January 18, 2020 Diverter valve? Quote Link to comment Share on other sites More sharing options...
Schmitty Posted January 18, 2020 Report Share Posted January 18, 2020 I'm not a heating engineer but have had my fair share of Baxi boiler issues through the years. First things first.... With the current cold ambient temperatures the hot water will likely not get as hot anyway... With a smaller output boiler (24-28kW) and a flow rate of 9-10 litres per minute the water temperature will rise by a given amount. If the starting temperature of the inlet water is colder then the outlet water will also be colder, unless you slow down the flow rate. As LG says, it could be the diverter valve..... Turn off your heating and allow the system to fully cool. Feel the temperature of the heating flow and return pipes to make sure it has fully cooled. With the heating still turned off, turn on the hot tap and let it run, slowly close the hot tap until you get the water as hot as possible. Does it get hot enough? If so it could just be the inlet water temperature being lower than normal or it could be the heat exchanger blocked. Leave it running for 15 minutes and then feel the flow and return central heating pipes. If they are hot then it's most likely the divert valve. Most of the manuals for the Baxi boilers are available online and have a fault finding section in the back as well as part numbers should you need spares. Disclaimer I'm not a heating engineering so feel free to ignore all the above!! Quote Link to comment Share on other sites More sharing options...
walshie Posted January 18, 2020 Report Share Posted January 18, 2020 Apologies if this is a bit obvious, but after our boiler was serviced last year the hot water was a lot cooler than it had been before the service. On closer investigation the engineer had turned down the water temperature but we couldn't see it as it's an external boiler and those controls are inside the cabinet. A quick turn of the dial and we were back to normal. Probably doesn't apply to you, but worth checking. Quote Link to comment Share on other sites More sharing options...
aga man Posted January 18, 2020 Report Share Posted January 18, 2020 I think Schmitty could be along the right lines. Presuming we are talking about a combi boiler, many of these boilers are fitted with a flow restrictor which can fail, particularly if you have quite high pressure cold mains. Reducing the incoming cold valve below the boiler {slightly} may improve temp at the taps. It could of course be one of a few things, diverter valve passing, plate heat exchanger part blocked, thermistor etc which would need an engineer to test properly. If the boiler is only a few years old maybe it still has warranty? perhaps your installer could get a repair done under that. Quote Link to comment Share on other sites More sharing options...
wigeon jim Posted January 18, 2020 Author Report Share Posted January 18, 2020 Thanks to the above,. The hot water in the kitchen near the boiler is not to bad ,you can just hold your hand under the hot flow but the hot in the bathroom above the kitchen is only half as hot even running a bath with only hot water its sill not hot enough,. Used to be OK as you needed to add cold water to the bath before,. Jim. Quote Link to comment Share on other sites More sharing options...
wigeon jim Posted January 18, 2020 Author Report Share Posted January 18, 2020 It's a Baxi platinum 33 combi Erp boiler Quote Link to comment Share on other sites More sharing options...
wigeon jim Posted January 18, 2020 Author Report Share Posted January 18, 2020 Just slowed up the cold supply coming into the house and it's now producing hotter water, so should I just keep it at that or should the boiler flow restrictor be doing that,. In the process of fitting a mixer shower at the moment but on hold till I know boiler will cope,.. Jim Quote Link to comment Share on other sites More sharing options...
aga man Posted January 18, 2020 Report Share Posted January 18, 2020 Should be ok at that as long as you are getting 12-13 litres a minute from the hot taps. Would best to get the flow issues checked when next engineer visits but should be fine for now as long as you are still getting near to those flow rates Quote Link to comment Share on other sites More sharing options...
seph234 Posted January 18, 2020 Report Share Posted January 18, 2020 As said above, more likely the diverter valve not seating properly or could be the plate heat exchanger. was the system flushed properly when the boiler was changed? Quote Link to comment Share on other sites More sharing options...
wigeon jim Posted January 18, 2020 Author Report Share Posted January 18, 2020 Just done a flow test, only getting 8 L.P.M. On hot tap Quote Link to comment Share on other sites More sharing options...
seph234 Posted January 18, 2020 Report Share Posted January 18, 2020 (edited) Thats a bit low it should be about 12/13 on that with boiler. do you have any type of water filter on the cold main before it goes into the boiler? is your water hard? i big give away is how much scale do you get in your kettle? the inside of your plate heat exchanger could be scaled up. Edited January 18, 2020 by seph234 Quote Link to comment Share on other sites More sharing options...
seph234 Posted January 18, 2020 Report Share Posted January 18, 2020 The other test should be carried out as Schmitty said earlier, to check if the diverter valve is bypassing slightly. let the boiler cool, turn on the hot water and see if the heating flow and return pipes get hot if they are then the diverter valve needs cleaning/replacing Quote Link to comment Share on other sites More sharing options...
Lord Geordie Posted January 19, 2020 Report Share Posted January 19, 2020 12 hours ago, seph234 said: Thats a bit low it should be about 12/13 on that with boiler. do you have any type of water filter on the cold main before it goes into the boiler? is your water hard? i big give away is how much scale do you get in your kettle? the inside of your plate heat exchanger could be scaled up. Would that not affect both hot water AND the heating side though? If the heating is getting hot, surely the water should do the same? My boiler used more gas heating water! The burner is at max during the process! But once the heating is on a min or so the burner scales back. Quote Link to comment Share on other sites More sharing options...
B725 Posted January 19, 2020 Report Share Posted January 19, 2020 It's probably a combination of lower incoming water temperature requiring more energy to heat it up and the PHEX scaling up, as someone has asked does it have a limescale inhibiter on the incoming cold supply and is the heating system clean and treated. Limescale and heat together quickly naffs things up. Quote Link to comment Share on other sites More sharing options...
seph234 Posted January 19, 2020 Report Share Posted January 19, 2020 5 hours ago, Lord Geordie said: Would that not affect both hot water AND the heating side though? If the heating is getting hot, surely the water should do the same? My boiler used more gas heating water! The burner is at max during the process! But once the heating is on a min or so the burner scales back. No, different heat exchanger for the heating and hot water. the hot water uses a plate heat exchanger which can get scaled up or sludged up if the heating circuit wasnt flushed properly. Quote Link to comment Share on other sites More sharing options...
Lord Geordie Posted January 19, 2020 Report Share Posted January 19, 2020 Ah I see. My boiler only has the one but having just looked it’s a dual channel one! Quote Link to comment Share on other sites More sharing options...
Saltings Posted January 19, 2020 Report Share Posted January 19, 2020 (edited) had to replace the diverter valve for the same problem heating fine lacking in hot water https://www.ebay.co.uk/itm/BAXI-COMBI-INSTANT-80E-80HE-105E-105HE-COMPLETE-WATER-VALVE-ASSEMBLY-248728/292602303239?ssPageName=STRK%3AMEBIDX%3AIT&var=591407355200&_trksid=p2057872.m2749.l2649 easy to fit problem solved about 1/2 hr to fit sent them back the old unit as service exchange Edited January 19, 2020 by Saltings Quote Link to comment Share on other sites More sharing options...
wigeon jim Posted January 21, 2020 Author Report Share Posted January 21, 2020 Thanks all again, will show my heating guy the link above when he comes on Friday ,👍 Quote Link to comment Share on other sites More sharing options...
seph234 Posted January 24, 2020 Report Share Posted January 24, 2020 Any news? Quote Link to comment Share on other sites More sharing options...
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