Washing machine hot water coming from Combi Boiler

[DFern90]

Evening,

This weekend I replaced our washing machine that had broken down with a brand new Samsung.

I thought all was fine but then during the start of one cycle I noticed that the combi boiler is firing up each time water is demanded by the washing machine. It fires on for maybe 5-10 seconds each time, then goes off until the next water is required.

While I cannot be 100% sure that this wasn't happening before, I know that it shouldn't be happening as water should be heated by the machine itself. However after hours of Googling etc I'm none the wiser as to why except perhaps something to do with pressure.

The washer only has a cold water in. The connections were exactly the same on the old washer (e.g also only cold in).

I tested our dishwasher next to the washer and this does not cause the boiler to fire.

Any ideas at all would be much much appreciated as I have literally no idea what to do/try.

Dan

 

[ianmcd]

run the washing machine and when you see the boiler firing up, feel the hose , if it gets warm it is plumbed in to the hot out let and not the cold inlet

 

[algas]

Its probably back pressure when the fill solonoid shuts off with with a snap action, you may have to fit a shock arrestor, some of the older combi's had them fitted integrally.

 

[DFern90]

run the washing machine and when you see the boiler firing up, feel the hose , if it gets warm it is plumbed in to the hot out let and not the cold inlet

I've put my finger in the detergent draw as water comes in and it is indeed warm on entry to the machine. I don't have easy access to the hose on the back of the machine - unless you meant on the boiler?
We only have one outlet on the pipe for the washing machine (cold) and there's nothing 'dead end'ed either.

 

[Madrab]

If it's only the fan that fires up for a few secs then there's probably a dead leg somewhere in between, when the WM draws on the cold it's send a pulse up the pipework, the dead leg then amplifies that pulse up to the boiler & the flow switch thinks there's a demand and fires up the fan ready to go and then shuts off when there isn't any draw.

 

[DFern90]

If it's only the fan that fires up for a few secs then there's probably a dead leg somewhere in between, when the WM draws on the cold it's send a pulse up the pipework, the dead leg then amplifies that pulse up to the boiler & the flow switch thinks there's a demand and fires up the fan ready to go and then shuts off when there isn't any draw.

Hi Rob, I can see the boiler igniting and the flame stays on until it shuts off again.

It's so annoying that I can't tell if it ever happened with our old washer. (I know it's not the washers fault but not sure if the change has caused the problem).

I have visions of getting a huge gas bill due to the gas being turned on every 10 seconds for about 5 minutes at the start of each wash and again during rinse cycle.

 

[DFern90]

Its probably back pressure when the fill solonoid shuts off with with a snap action, you may have to fit a shock arrestor, some of the older combi's had them fitted integrally.

Just Googled this as had no idea what they are and definitely might be worth a shot, thank you. We definitely suffer with 'water knock' when the machine draws water and shuts off. Potentially part of the same issue?

 

[Madrab]

Ah ok, if it's staying lit until the WM stops filling then it is drawing hot water. The WM has obviously been connected to the wrong valve then. WM's used to have hot and cold inlets and it wouldn't be the first time someone has plumbed the WM up to the now redundant hot feed rather than the cold feed, especially if it has a blue lever fitted (or no lever), by mistake..

Probably cheaper than using the internal element to heat the water tho TBH

 

[DFern90]

Ah ok, if it's staying lit until the WM stops filling then it is drawing hot water. The WM has obviously been connected to the wrong valve then. WM's used to have hot and cold inlets and it wouldn't be the first time someone has plumbed the WM up to the now redundant hot feed rather than the cold feed, especially if it has a blue lever fitted (or no lever), by mistake..

Probably cheaper than using the internal element to heat the water tho TBH

Yeah it does have a blue lever. There isn't like a second valve next to it though so not sure where else it could be plumbed too.

True - however I'm more worried about putting lots of stress on the boiler by having it trigger on and off 10+ times per wash.. can't be too healthy for it.

 

[dilalio]

Connect another washing machine hose to the valve and run it into the sink or a bucket. You'll soon know if it's connected to the hot supply.

 

[Harry Bloomfield]

It reads as if originally there was an hot and a cold feed installed for just one machine - a washing machine. The dishwasher added later and no one bothered to install an extra cold feed for it, so they transferred the WM to the hot feed using the cold for the dish washer.

It is not a difficult job to add an extra cold outlet.