What shower works best with low hot water pressure Combi?

[eastender3]

I wonder if you knowledgeable people can help me, please.

I live in a council flat and our hot water pressure is very low with a Modena combination boiler. The main problem is with having a shower or a bath. The council blames Thames Water for reducing the pressure few years ago to reduce leaks but then I contacted TW, they told me they don’t do that to prevent leaks. Don't know who to believe?

At the moment I have a basic mixer shower but hot water cuts out after a minute or two of hot shower than it’s cold water all the way, with kids screaming of cold water!

With my combi boiler what are my options of fitting which types of shower and do I need to check other plumbing that might restrict the hot water pressure.

Can power showers work with low hot water pressure and do some come with built in small pumps?

What about electric showers, don’t know much about them, will they a be better bet?

I’m completely lost with this and been suffering for months with this problem.

The Council technial guy, told me power shower would be easier to install due to current plumbing location but questioned if it'll work with my combi boiler.

 

[muggles]

If the hot water's cutting out then it sounds more like a boiler problem than a problem with the shower. Have you tried running a hot tap for a similar amount of time to see if it cuts out with that as well? Failing that it could be a problem with your mixer not working properly but I would expect it to be more erratic if this were the case.

You should ideally have a thermostatic mixer with a combi boiler.

If you're finding you're getting poor hot flow, or the hot flow is significantly less than the cold flow, then you have one of two problems - either you have a cr@p boiler that isn't capable of delivering a high flow of hot water, or you have a scaled-up heat exchanger (or in your case possibly both, it's not a great boiler....) Which version of the Modena is it?

Power showers need to be fed off low-pressure hot and cold supplies and are not suitable for fitting to systems run off a combi, as they have built-in pumps designed for pumping from a tank/cylinder. An electric shower might be an option, it'll require both a plumber and an electrician to install it though, a good one won't be cheap, and your electrician will need to confirm that you have an adequate electric supply to cope, some council places and older houses don't.

Hope this helps

 

[eastender3]

If the hot water's cutting out then it sounds more like a boiler problem than a problem with the shower. Have you tried running a hot tap for a similar amount of time to see if it cuts out with that as well? Failing that it could be a problem with your mixer not working properly but I would expect it to be more erratic if this were the case.

You should ideally have a thermostatic mixer with a combi boiler.

If you're finding you're getting poor hot flow, or the hot flow is significantly less than the cold flow, then you have one of two problems - either you have a cr@p boiler that isn't capable of delivering a high flow of hot water, or you have a scaled-up heat exchanger (or in your case possibly both, it's not a great boiler....) Which version of the Modena is it?

Power showers need to be fed off low-pressure hot and cold supplies and are not suitable for fitting to systems run off a combi, as they have built-in pumps designed for pumping from a tank/cylinder. An electric shower might be an option, it'll require both a plumber and an electrician to install it though, a good one won't be cheap, and your electrician will need to confirm that you have an adequate electric supply to cope, some council places and older houses don't.

Hope this helps

Many thanks for you reply.

The combi boiler is Modena 80E and is about 8 years old. Do you think the flow of hot water is a result of low water pressure as well, as my cold water flow is ok? Or as you mentioned, it could be due to the poor boiler.

Is the scaled heat exchanger inside the boiler? sorry don't much about them. I know some of our residents in the block have changed these boilers to Valiant models.

Is the thermostatic mixer shower a type of electric shower and if it is, then what models would you suggest, as I heard some models with low power, works best with low water pressure.

Finally do you think it's advisable to purchase one, with my current combi boiler situation, I mean will it satisfactorily work, in existing situation?

Have not tested the hot water bath tap contiously to check if cuts out, if it does not cuts out, then you're suggesting the problem could lie with the mixer shower. Mind you, the flow of hot water from bath room tap, is very weak compared to cold water flow.

Thanks for your kind help.

 

[muggles]

If your cold water flow is fine then it's definitely a boiler issue. Put a bucket or jug of known capacity, the bigger the better, under a convenient hot tap (doesn't really matter which one) and time how long it takes to fill it with the tap full on. This will give some idea of how your boiler is performing. Do this again on the cold side for comparison and post the results of both here. The Modena 80E doesn't give spectacular performance but it isn't too bad, I suspect there's some kind of fault there as suggested. Also try running your hot tap for 10 mins and see if the boiler cuts out.

You're quite correct, the heat exchanger is inside the boiler.

The thermostatic mixer is not an electric shower, it's a mixer like you have now except it will compensate the temperature when someone turns a tap on elsewhere, they should be fitted to combi boilers as they're better for preventing scalding/freezing. The Mira Combiforce is worth a look, been around for years, fairly bulletproof and spares are easy to get.

I think you should do the tests with your taps as suggested before you commit to doing anything, posts the results here and it'll be easier to advise from that.

 

[eastender3]

If your cold water flow is fine then it's definitely a boiler issue. Put a bucket or jug of known capacity, the bigger the better, under a convenient hot tap (doesn't really matter which one) and time how long it takes to fill it with the tap full on. This will give some idea of how your boiler is performing. Do this again on the cold side for comparison and post the results of both here. The Modena 80E doesn't give spectacular performance but it isn't too bad, I suspect there's some kind of fault there as suggested. Also try running your hot tap for 10 mins and see if the boiler cuts out.

You're quite correct, the heat exchanger is inside the boiler.

The thermostatic mixer is not an electric shower, it's a mixer like you have now except it will compensate the temperature when someone turns a tap on elsewhere, they should be fitted to combi boilers as they're better for preventing scalding/freezing. The Mira Combiforce is worth a look, been around for years, fairly bulletproof and spares are easy to get.

I think you should do the tests with your taps as suggested before you commit to doing anything, posts the results here and it'll be easier to advise from that.

Thanks very much for your kind reply.

I'll do the test as you suggested and get back to you.

 

[eastender3]

If your cold water flow is fine then it's definitely a boiler issue. Put a bucket or jug of known capacity, the bigger the better, under a convenient hot tap (doesn't really matter which one) and time how long it takes to fill it with the tap full on. This will give some idea of how your boiler is performing. Do this again on the cold side for comparison and post the results of both here. The Modena 80E doesn't give spectacular performance but it isn't too bad, I suspect there's some kind of fault there as suggested. Also try running your hot tap for 10 mins and see if the boiler cuts out.

You're quite correct, the heat exchanger is inside the boiler.

The thermostatic mixer is not an electric shower, it's a mixer like you have now except it will compensate the temperature when someone turns a tap on elsewhere, they should be fitted to combi boilers as they're better for preventing scalding/freezing. The Mira Combiforce is worth a look, been around for years, fairly bulletproof and spares are easy to get.

I think you should do the tests with your taps as suggested before you commit to doing anything, posts the results here and it'll be easier to advise from that.

Hi 'muggles'

I managed to do the test, as you requested.

On bathroom cold water tap 5 litre. Took about 28 seconds to fill it up. Hot water it took much longer; 1 minute and 35 seconds.

I run the hot water tap for more 10 minutes and it didn't cut out.

We don't normally use the full bath, for our family bathing, as it takes too much time and quite a lot of hot water but use the basic mixer shower instead.

What do you think?

Thanks.

 

[muggles]

OK your cold is delivering 10.7 litres per minute, which is a bit below average but quite acceptable. Your hot is delivering 3 litres per minute, which is rubbish and far below what your boiler should be capable of, your hot should actually be just about the same as your cold.

Definitely a boiler fault, time to call in an engineer

 

[Whitespirit66]

Before you go any further, make sure that any valves on the cold supply into the boiler, or hot out of the boiler are fully open. Also check for any isolating valves to the shower/hot taps.

 

[glasgowjim81]

it sounds like you have a blocked filter in your boiler .im sure a ferroli modena should produce 8 or 9 litres per minute

 

[eastender3]

OK your cold is delivering 10.7 litres per minute, which is a bit below average but quite acceptable. Your hot is delivering 3 litres per minute, which is rubbish and far below what your boiler should be capable of, your hot should actually be just about the same as your cold.

Definitely a boiler fault, time to call in an engineer

Thanks for your reply. What do you think the problem might be in boiler, you suggested heat exhanger, is that the problem or a blocked filter?. So that I know when I call the engineer I know what the problem is, as sometimes these engineers try to fob you off and say something differant and unnecessary purchase of expensive parts replacement.

Thanks.

 

[muggles]

You've been watching far too much Rogue Traders. I can't say what it is without looking at it, could be the hex, could be the filter, could be something else. Get someone in who's recommended by a friend or neighbour

 

[bengasman]

When did this problem start? Is there a tank somewhere in the loft by any chance?

 

[eastender3]

When did this problem start? Is there a tank somewhere in the loft by any chance?

Thanks for your comment.

The problem started a last year. I live in a purpose built council flat. I have a combi boiler, and there is no seperate tank in the flat. Wanted to know if it's the low water pressure or the boiler, that causing the problem. My cold water flow is fine but hot water flow is slow. I might get someone to look at shower tap and stopcock in the bathroom.

Thanks.

 

[bengasman]

Sounds like the boiler is connected to the communal storage tank; they usually are somewhere near the top of the communal stairs.

 

[eastender3]

I called an engineer last week; he replaced 1 thermister and cleaned the filter. After that it he tested the hot water, and at the time it was working ok. But in the past it was always a intermittent problem with hot water. Now after 2 days later, we have the same problem; sometimes there is not hot water and the boiler fails to ignite but after several stopping and starting the hot water tap, then it ignites and hot water comes.

Not sure what the problem is. I looked at the Modena 80E manual, it says about the flow switch. Now I have to re-call the engineer, and argue that he shouldn’t charge me again for the call out.