Converting from regular boiler to system boiler - bad idea?

[highfives]

Background context: small, 2 bed terrace house. One bathroom (1 bath with electric shower). Kitchen, no utility room so just one sink outside of bathroom. I live here alone now, but who knows what the future holds. (Most of the other people in these houses are young families who start their families here then move on - which I'm keeping in mind if I have to sell rather than living here until I die).

I'm disabled and struggle to cope with maintenance. Had a couple of recent water leaks including one from cold water tank in loft (an age/wear and tear issue).

I really want to reduce the amount of things to maintain / that can go wrong as the recent situation has shown me how vulnerable I am as a disabled person if an unexpected plumbing problem renders my home uninhabitable without warning again.

My boiler is approaching the end of its life anyway so I have started researching my options. I am feeling stressed out by the amount of pipework and extra tanks that come with an open vented system, because (right now at least) it just feels like I'm increasing the number of potential sources of future leaks and stressful situations.

I've more or less ruled out converting to a combi (which was my original wish as I could have lost all the tanks and the cylinder) due to amount of work and limitations.

I'm wondering if converting to a system boiler and losing the loft tanks is a good compromise or a terrible idea that I will regret!

Has anyone done it? What was your experience? Was it worth it? Do you regret it? Am I opening myself up to a new set of problems?

Hi, given the size of your property and you only have one bathroom I would personally go for a combi boiler. I have had a system boiler in a larger property and they require more maintenance and storage for the hot water cylinder, they are great if you have more than one bathroom and two showers are running concurrently. I have also had a few combi’s in my lifetime and have always been greatly impressed with their efficiency and reliability. Hope this helps.

I had a combi boiler in a two bed flat (one bathroom, one kitchen) and it was the simplest thing ever. I had it has checked most years and it never gave me any bother at all, nor needed any maintenance.

We have a closed system condensing boiler in our house now. It's very reliable, but is a bigger beast (for a bigger house!) and has a lot more things to tweak, balance, maintain. And the hot water tank is another thing to store, whereas the combi is just the one "box".

I'm not a fan of combi boilers but given the size of the house and you have an electric shower it would probably be a no brainer.

In any event, yes years ago we converted a vented system to a pressured system. Excellent idea. Get rid of the tank in the loft that feeds the system (the cold water supply for the hot water cylinder remains). Means if there is a leak, even minor you know about it as the pressure drops.

But personally, if you are wanting to get rid of tanks then the combi is best as the large storage tanks all go from the loft as well as the water cylinder.

Whoever you decide, you will prob see decent savings from changing the boiler....I've seen a reduction of at least 30% in my bills and it has been very cold since I changed it

Combi boiler and get rid of the electric shower - they use a huge amount of electricity.

Ansolutley a combi and use it for the shower. Its exactly what theyre designed for.
I found speaking to a company called boxt (details online) really helpful as to what was most suitablefor us. They definitely gave better acvice than any orher boiler company too.
Why dont you want a combi out of interest?

Oh thanks all, that's really helpful.

I'd been reading that to convert to combi that the inlet valve on toilet would need replacing (which would mean taking whole toilet off the wall), taps might all need replacing or altered pipework, wouldn't ever be able to have a pump shower, and that it the system wouldn't cope if I ever had another person here.

Example I kept reading was that if someone tried to turn the kitchen tap on to do washing up while someone was in the shower then the person in shower would either get scalded or frozen.

Followed by lots of discussions that came up when I was googling by people saying converting to combi is a bad plan and combis are unreliable.

Great to hear some more positive experiences of system and combi.

A combi boiler will be fine for your needs. It's only once you want to start running two showers at once that it's an issue. We have a slight drop in pressure if someone turns a tap on, flushes the toilet etc. but no temp issue. Still a million times better than an electric shower. Generally, you only need a pump shower if you have a tank, if a combi you should have enough pressure anyway so that shouldn't be a reason to put you off.

Combi definitely I would say - I've had a combi in a 2 bed with one shower and a 4 bed with 2 showers. Slight loss of temperature in the 4 bed when 2 showers on. The 2 bed was absolutely fine.

We've got a megaflo now - bigger house - but the tank is huge - we gave up a toilet for it.

New combis are much better than the old ones - so talk to people who have had recent experiences. I don't know why your toilet would have to change...

Example I kept reading was that if someone tried to turn the kitchen tap on to do washing up while someone was in the shower then the person in shower would either get scalded or frozen.

This is just not true any more. You buy a nice thermostatic mixer shower and whilst the pressure might drop if someone else runs the kitchen tap, the shower will not go very hot or very cold.

Hello - I am about to pull out my tanks & replace with a combi in a new house for a number of reasons (getting rid of tanks and so risk of them leaking is #1). Its also impossible to clean out my water tank due to awkward access which is also driving my decision. Also in a 2 bed house, with 2 bathrooms.

For a small household, even up to say 3-4 i'd say a combi is fine. I had a combi in a 2 bed flat for 10 years: the shower thing can be annoying (they do go hot/cold if someone else turns a tap on) but in a 2 bed house you tend to realise that someone is in the shower :). I've had a few quotes and its coming to about 4.5 K for my boiler/all the removal (this is London)

I've had v good plumbing company in to quote: said nothing about toilet, did mention that some electric showers (with a pump) are not ok to use with a combi, and main concern: the changeover MAY result in leaks (but then I am worried about an old/redundant system leaking). New combis tend to come with 7-10 yr guarantees: I had a valiant and that guarantee was transferable when I sold so that is a good thing in my book

@YellowFish12: thanks for info re thermostatic mixer, will make sure I am getting one of those

I kept reading was that if someone tried to turn the kitchen tap on to do washing up while someone was in the shower then the person in shower would either get scalded or frozen.

This used to happen at my parents house with their electric shower.

I do think you would be better off with a Combi.

if @PigletJohn is around - he would be able to give you some very sound advice.

I have a combo in a four bed with two bathrooms, your plumber should spec the combo for the size of your property, it’s absolutely your best option for a flat/small house, you’ll lose all those stored water tanks, the only downside is you lose your airing cupboard heat, not sure who told you you need different taps, I have waterfall, your taps won’t make any difference to a modern boiler

@DespairingHomeowner

I think you have added a different question onto the original thread, you would do better to start a new one as there will be a mixture of different information and responses to different people otherwise.

hi @PigletJohn: I agree with your point, but I'm not actually asking a question.

Perhaps my post was unclear: I was just mentioning to the OP that my heating company have said that there is a risk that the changeover may result in a leak (in my case, I am going to leave a short gap between decorating /carpets etc in case it does), so that is something to think about

The shower going hot/cold is nothing to do with the type of boiler. If you have an electric shower without thermostat it will always change temperature if you run any tap (hot or cold) or flush the loo. If you are on your own it doesn't matter. None of the things you have stated about changing to a combi was true when I changed..no new taps or radiators/pipework needed, no work on toilet. If you want to be able to run more than a couple of taps at once you just buy a bigger boiler. Combi boiler + electric shower is a good combination. There is a risk of leaks from existing radiators because they have to flush all the sediment out of them and that may be the only thing blocking a hole. But you'd find out about such a hole and have to fix it eventually anyway.

If you are thinking of changing to either a combi or an unvented cylinder, start by measuring the incoming water flow.

Fill a bucket at the kitchen cold tap, and the garden or utility tap if you have one, time it, calculate litres per minute.

Example I kept reading was that if someone tried to turn the kitchen tap on to do washing up while someone was in the shower then the person in shower would either get scalded or frozen

This happens with my combi but admittedly we don’t have a thermostatic valve, just a shower attached to the bath taps.

@HopeClearwater

that is one of the things that can happen if you have insufficient water flow to satisfy all the taps that may be used at the same time, hence my question is important before changing.

Even in a 1-bathroom house with one occupant, it can happen if, for example, the washing machine starts or stops filling while you are having a shower.

Flow is not the same as pressure.

Ok, rapidly realising how much I don't know on this subject. Looks like I've been getting lots of different things mixed up.

Flow rate seems to be bang on 10 litres per minute. She says, hoping her maths skills don't turn out to be as terrible as her plumbing/boiler knowledge.

10lpm is not enough.

Yeh, that's what I thought from googling it afterwards. Damn.

Thanks for your help.

@PigletJohn I didn’t know that. I thought flow rate would be the same as pressure. I’ll have to investigate this further. Thank you.