Washing Machine Not Filling With Hot Water
We have just had a new combi boiler fitted and noticed that our washing machine is not filling up correctly. It fills up correctly on rinse but doesn't seem to fill up from the hot tap. Could it be something to do with the inlet pressure / temperature of the hot water? The boiler needs a min pressure drop of 0.5bar to start heating the water
Any advice would be gratefully recieved.
Solution Summary
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Washing machine hot fill issue after combi boiler installation
- The problem
- After a new combi boiler was fitted, the washing machine appeared not to fill correctly on hot wash programmes, although it filled on rinse. The concern was whether the new hot water supply pressure or boiler operation was affecting the machine.
- Likely cause
- The strongest diagnosis in the thread is reduced or inadequate water pressure to the washing machine when hot and cold supplies are used together after the combi installation. Plumbing restriction or pressure adjustment after the boiler change was considered more likely than a blocked filter. A washing machine fault was mentioned as a possibility only if a proper supply was confirmed.
- What fixed it
- The advised action was to check whether the machine filled on a hot-only programme, confirm water flow from the hot hose, and clean the inlet valve filters. After the poster reported that both filters were clean and flow seemed fine individually but dropped when both supplies were used together, the recommendation was to increase the water pressure to the washing machine slightly if the supply taps were already fully open. No final repair confirmation was posted.
- Checks to try
- Ran a cold rinse and observed water level
- Ran a whites cycle and observed water level
- Cleaned both filters in the water valves
- Tested water flow from the supply as advised
- Observed that cold water pressure dropped when hot and cold were operated together
- Noted a squeak from the cold water inlet valve during cold rinse
- Parts or tools mentioned
- Water valve filters
- Fill hose
- Bucket
- Pair of pliers
Safety: Further diagnosis should be carried out by a suitably qualified appliance engineer.
3 Answers
Usually, the water supply to the hot water valve should increase in pressure when a combi boiler is fitted because it gets supplied with cold water mains pressure. Maybe somethings gone wrong with the plumbing . Did the washing machine get moved at all? In this case a kinked hot water fill hose could be the problem.
Put the washing machine on the whites program. This is a hot fill only wash. If no water comes in, then listen carefully for a gentle humming noise. If you hear one, this shows the hot water valve is being energised but there is no water supply.
To check that water is actually available through the plumbing from the offending pipe. Turn off the hot water tap and unscrew the hose from the valve at the back of the washing machine. Then simply hold the hose over the sink or into a bucket and turn the tap back on.
If water comes through at a decent flow rate then check the filter in the water valve on the washing machine in case it's blocked. You can pull it out with a pair of pliers and clean it. However, this would only explain your fault if it is severely blocked up which is rare.
If there is a proper water supply to the hot water valve, then fault is likely to be with the washing machine. Let me know what you find and we can investigate further if necessary.
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Thanks for your advice.
I have cleaned both filters in the water valves and tested the water flow as mentioned. Both seem fine. Until operated together and then the cold water pressure drops. I ran the washing machine on a cold rinse, and the water rose to about 1cm above the bottom of the door. I then ran it on a whites cycle and the water also rose to about 1cm below the door.
I will set a chair up infront of the washing machine tonight and watch it through a normal cycle to see if it has improved. One other thing that I noticed was there was a squeak from the cold water inlet value during the cold rinse.
It sounds like the water pressure to the washing machine isn't quite high enough. When you have a combi boiler fitted, the hot water system, which is normally gravity fed (from the hot water tank) is replaced by mains pressure cold water which is heated up on demand. The installers of the combi boilers sometimes find that leaks are introduced on the hot water system because of a virtual doubling of pressure. Because of this, they may turn the water pressure down.
Your tests indicate that the washing machine fills up OK on hot fill and cold fill separately, but when filling together the flow drops. This indicates the water pressure needs turning up to the washing machine. If the taps are already on full (to the washing machine) then turn the mains water pressure up slightly.
Just turn it up enough to get a decent flow of water coming into the machine on a hot and cold fill programme like non fast coloureds
( Related links: no water goes into washing machine) )
NOTE: Most modern washing machines are now Cold fill only
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