Replacing a gas hot water cylinder - infinity versus cylinder versus electric cylinder?

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jonathan18

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#204543 6-Oct-2016 10:55

This morning my wife advised me our gas hot water cylinder's playing up - making weird noises and leaking (well, until the gas and water were turned off).

My thoughts are, even if it is repairable and those repairs are affordable, it's probably time to replace the cylinder as it's old and is full of crud resulting in often brown water (posted here seeking advice on this previously).

So - the main question I have is: do I replace it with another gas hot water cylinder, switch to an infinity-style gas system, or replace it with an electric cylinder?

I'm tempted by the infinity-style system, but have concerns regarding:

* price - are purchase/install costs considerably more than a cylinder? Are they so much more efficient that this cost difference will be paid back over time?

* location - can it be put in the hot water cupboard and flued externally, or does it need to be on the outside wall?

* efficacy - is the hot water they produce adequate for operating two showers at once, say?

* brands/models - any ones in particular that stand out, ideally looking at value for money?

In regards to a cylinder:

* what size would I need for a family of four plus allowing for guests? The current cylinder is only 150l, and TBH we sometimes do run out of hot water if we have guests (we also have boys who will be teenagers in a few years - I'm guessing infinity style supply would be best for this eventuality).

* in regards to switching to electric: I'm thinking this is only worth it if we're going to turn off the reticulated gas. Doing this would only leave gas being used for the kitchen hob, as the two gas heaters get little use since we put in a ducted heat pump. I'm not sure of the feasibility of converting the hob to run off LPG, given it's a minor brand (Indesit) so not sure of ability to get the proper jets, and replacing it's not an option as it's combined with the oven.

Edit: to add that we're with Flick for electricity, so have the potential to build in from the get go appropriate timer controls to make the most of cheaper night rates - if that should be an influence on the decision?

Appreciate any thoughts you may have on the relative merits of the options, and also hopefully some answers to the questions above.

Many thanks

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#1646468 6-Oct-2016 11:11

You should probably do up a spreadsheet for costs of electric vs gas. If you go electric include the cost of replacing all gas appliances. You'd probably want a larger cylinder, 250 - 300L. It's not like there's any big disadvantage of larger cylinders, they might lose a little more heat but I wouldn't think that much, so the only downside is purchase price. I suspect electric will be more expensive than gas. Electric cylinders look to be $1500 - $2000. A new stove is $2000 or so for a decent induction one.

With gas instant hot water sounds fine. You can install more than one gas continuous flow heating system, one per shower for example. Some prices for the parts here, around $2000 for a cylinder or $1200 per continuous flow system.

Replacing the old gas cylinder with a larger new gas one is probably going to be easiest and cheapest.

davidcole

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#1646514 6-Oct-2016 11:38

We run two showers off one 26L (per min I think the rating is). I'll possibly look at a 2nd for our ensuite only to reduce the delay, but it handles it. We're a bit affected if we leave the temp higher and require mixing. But it you add controllers you can set the temp of the hot water exactly, and then not require any mixing, IMO this is a more efficient way of operating as you're only heating the temperture to what you want, and not over heating it then cooling it down. The disadvantage is if csomeone whats to do the dishes, they're stuck with 42 degree water (the kitchen you can push up to 55 deg) with an override.

In terms of running costs, I'm unsure, this is my 2nd house that we've converted to continuous. But they were both previously electric (the first house only had a single cylinder, then 2nd had 3 to be replaced). I understood the install costs for infinity about $2.5k (for the unit and to hook it to the hot water system).

Unsure about installation inside - I think I've heard of it being internally installed and flued. But I generally though it was externally installed.

There are other brands, but I've only used the Rinnai systems.

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Camden

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#1646564 6-Oct-2016 12:16

We had a 260sqm house with four people and an electric 270L water cylinder. Wife always complaining that the water was too cold for a hot bath at night.We ran the cylinder on night rate power. We extended the house by another 100sqm to 360sqm so took out the cylinder and replaced it with a Rinnai Infinity XR26ia Gas unit. This only heats the water when you turn the tap on with no storage. This unit has worked very well over the last five years. The water pressure drops just slightly if two people are useing two showers at once,but not enough to cause any detrament to having a good shower.

In Christchurch we don't have reticulated gas so have to run it on LPG cylinders. Four showers, sometimes five or six, one or two loads of washing on warm setting,one load in the twin drawer dishwasher per day and say three to four baths per week, we go through two tanks per month.

That's $215 per month plus about $100 per year to hire the cylinders. I think from memory that the unit cost about $3500 to buy including install. we have a walk in roof space storage area so put the unit on some timber brackets mounted to the roof framing.It is flued out though the roof.

One thing about instant hot water over storage system is there now no delemore over turning the cylinder off to save power if you are going on a short holiday then having to wait for ages till the cylinder warms up again on return home.

In our case I did not go too far in comparing the running costs as we wanted good hot water service first and costs came second. The only thing you have to remember is constantly check the flag on the bottles to order replacements which is a bit of a pain.How ever we have only run out twice in five years and we hook up the BBQ bottle till the big ones are filled again.

jonathan18

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#1646570 6-Oct-2016 12:26

Thanks for the feedback guys.

Rough idea of costs from the plumber are:

* replace gas cylinder: 2-2.5k

* external Infinity system: 2.5-3k

* internal Infinity system: 3-3.5k

So it does appear (and confirmed by the last post) that the Rinnai models can be fitted internally (or there's a different model?); the increased cost is primarily due to the flue.

I'd imagine there'll be less difference between the internal and external costs at our place, as there's no way we'd have the box right next to the back door (which is where the hot water cylinder backs on to), so there'd be additional costs to move the pipework to another wall. That said, they said they'd need to upgrade the gas main to ensure adequate flow is available.

I hear what you say re the advantage of the controllers but aren't they likely to add a decent amount to the cost? Can they be retrofitted if we decide later we should have put them in in the first place? I'm mindful the basic cost is already a lot of money for us, so need to justify the additional expense - as it is, the benefits of an instant system, especially the cheaper on-going running cost, make this probably worth it over a cylinder, but finding the additional money for this cherry on top may be harder to justify!

At this point we're tempted to go with the Infinity (he's also talking the 26l version), and will decide internal versus external based on the difference in cost.

robjg63

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#1646578 6-Oct-2016 12:37

So the costs above include the heater/cylinder?

We have had a Rinnai Infinity (think its a 24) in our house since we built in 2002.

It just works.

They heat up pretty quick and you arent heating water when you dont need it.

On the odd occasion when a second hot water tap gets turned on, there is a slight drop off in temperature for a few seconds until the unit cranks up the heat a little more to compensate - but its not like you suddenly get a cold shower. The 26 would probably be a bit more resilient.

The neighbor has an older villa and they have their unit installed flush in the wall. There is just a vent slot on the outside of the house.

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Camden

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#1646636 6-Oct-2016 13:49

I forgot to mention the controllers. When we had our Rinnai unit installed the gas fitter said they were not nessasary but if we had second thoughts they could be retrofitted. We did not fit one as with three bathrooms I thought that there would never be one temperture set to please everyone. Weather they would lower the running costs, I don't know. We just set the shower control to suit. Again from memory, I think they were about $200 plus fitting and wiring. After five years use we have not missed any remote temperture control.

We had the option of getting an external unit screwed to the exterior of the house but as we had the roof space available we chose that option, as the circulation of hot water from the unit was more centralized.

jonathan18

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#1646640 6-Oct-2016 13:58

Thanks for all the feedback; it's certainly help cement our decision to go with an Infinity system. I've just met with the plumber - he said he'd installed one gas cylinder in a new build in the last 10 years, which gives an indication as to what the current preference is for!

Yep, those prices include the cost of the unit, whether it be cylinder or heater, removal of the old cylinder, and upgrade of the gas line (tapping in close to the road).

He's just emailed through a site-based estimate: $2944 for the 26 litre external model (that's installing it around the corner so shifting the gas line, which they said will still be cheaper than installing the internal model - this way it also frees up a large amount of space in the cupboard).

I asked for a price of a larger capacity unit (32 l/sec I think), but that's an additional $960 which is significant. While we have three bathrooms, the third is in a separate building so the chances of all three showers going at the same time are slight and not worth an additional $1k I don't think.

Good to know the controllers can be retrofitted if need be, but it seems like they aren't at all critical and will certainly save a decent amount of money.

Given we're without hot water until it's done, they've agreed to fit us in to have it done tomorrow, otherwise it'll be a whole weekend without it!

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davidcole

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#1646642 6-Oct-2016 14:03

Also remember, re the unit size....if you really wanted to you could retrofit a new unit. Given they don't cost that much more in running costs (just the install), you could run multiples if needed. It'd shorten the lag time if it was near a particular room.

You'd just break that room from the main hot water supply and feed it from a dedicated unit. But most people just put up with the slow lag time.

But if you're replacing one cylinder with one unit, the lag time is probably the same.

Amosnz

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#1646655 6-Oct-2016 14:13

We are doing a similar thing ourselves, replacing a gas cylinder with an external infinity (brought the VT26 infinity unit at a sale a few months ago, but haven't organised the install yet). Getting the cupboard space back is a definite benefit.

A couple of things to note:

You can have a maximum of 4 controllers of which only 1 controller can set a 55deg temp. We have hot taps in the kitchen, bathroom, laundry, ensuite and garage so one of these places wouldn't be able to have a controller. If you went into the laundry and the temp wasn't 55deg, you'd have to go out to the kitchen to override it, then back to the laundry. The garage is even further away so we felt having controllers would be a hassle (but we will install conduit for the cables in case we decide differently in the future).

Not installing controllers gives you slightly less warranty. https://rinnai.co.nz/attachments/docs/cfwh-warranty-v3-03-16-2.pdf

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jonathan18

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#1646657 6-Oct-2016 14:17

Amosnz:

We are doing a similar thing ourselves, replacing a gas cylinder with an external infinity (brought the VT26 infinity unit at a sale a few months ago, but haven't organised the install yet). Getting the cupboard space back is a definite benefit.

A couple of things to note:

You can have a maximum of 4 controllers of which only 1 controller can set a 55deg temp. We have hot taps in the kitchen, bathroom, laundry, ensuite and garage so one of these places wouldn't be able to have a controller. If you went into the laundry and the temp wasn't 55deg, you'd have to go out to the kitchen to override it, then back to the laundry. The garage is even further away so we felt having controllers would be a hassle (but we will install conduit for the cables in case we decide differently in the future).

Not installing controllers gives you slightly less warranty. https://rinnai.co.nz/attachments/docs/cfwh-warranty-v3-03-16-2.pdf

Good information to know, thanks.

BTW, what did you pay for the VT26 on special? The plumber says they're $1,100 incl GST, so assume that's what they'll charge it to us for. (The bigger unit was $1789 + GST!) Not sure if it was worth buying it ourselves and getting them to install it...

Amosnz

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#1646659 6-Oct-2016 14:17

davidcole:

But if you're replacing one cylinder with one unit, the lag time is probably the same.

I believe the lag time is slightly longer as the unit takes ~10 seconds to start flowing hot water, then add on the previous time to flow from the unit to the tap.

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Amosnz

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#1646664 6-Oct-2016 14:28

jonathan18:

BTW, what did you pay for the VT26 on special? The plumber says they're $1,100 incl GST, so assume that's what they'll charge it to us for. (The bigger unit was $1789 + GST!) Not sure if it was worth buying it ourselves and getting them to install it...

Pretty sure ours was about $1100 incl too. It was several hundred off the normal trade price (at least here in New Plymouth). We have a friend whose a plumber (we get parts at his cost and cheaper labour) and this was less than he could get it for.

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mdf

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#1646666 6-Oct-2016 14:31

Continuous hot water on reticulated gas is IMHO a no brainer if you have the option. As others have said, never running out of hot water and mains pressure showers (though you can do this with the right cylinder too) are *awesome*. We've just finished our second conversion (we did our previous place too).

In terms of internal vs external, the flueing is the main difference but there are some other differences too (e.g. weather proofing). You should aim to use an internal unit inside and an external unit outside really. We've just mounted a new internal unit in the subfloor, as we're coastal and so get plenty of salt.

For the size, continuous hot water heaters are rated on a litres per minute at a 25 degree rise. That is, how much water per minute can it raise 25 degrees over ambient. Most people shower at 37-42 degrees. Flow depends on the shower head, but 13L/minute is a pretty luxurious showerhead (though not a rainfall shower head). So say you liked a 40 degree shower, and lived in an area where ambient was 15 degrees (note that this is basically the pipe temperature, not the outside temperature), aim for at least a 13L/min unit for one shower, 26L/min to two at once. We're in Wellington and a 27L/min unit has been more than enough for two showers at once so far.

You can heat water smarter too using a controller. By default, most units will heat water to 50 or 55 degrees. You then have to mix in cold at the shower to get the temperature acceptable. But obviously if you're heating water *more* than 25 degrees will reduce the flow rate. So you'll get more water per minute heating it only to 40 rather than 50. Depending on your plumbing you might be able to even this out at the showerhead, but it works well for us to lower the temperature prior to showering and then using the shower essentially on full hot.

We've got kids and the new controllers also have a bath fill function. Press a button and open a hot tap and it will fill the bath to a pre-defined volume. No more forgetting and flooding the bathroom.

In terms of cost, it was substantially cheaper for us to install a continuous unit than replace existing hot water tanks. Our plumber told me this was because we needed to replace a lot more valves (and other plumbing bric-a-brac I'd imagine), whereas we could just bang in a continuous unit using mains. We did need to replace one tap entirely and fiddle with the valves on others to deal with the low pressure/mains pressure change.

Have a look at energy efficiency too. The newer condensing units capture the waste gas and use this to preheat the water leading to efficiency gains. We went with a middle of the range efficiency model, which had the added bonus of lowering the exhaust gas (because it was in the subfloor, the flue was a bit inconveniently located for super hot steam).

We ended up with a Rheem (sometimes branded as Paloma) model instead of a Rinnai (Bosch is the other major brand). According to Mr PlumberMan, they're all much of a muchness and usually amounts to whichever the plumber concerned has the most experience with. They all bring out new models all the time and are constantly leapfrogging each other. We went for the Rheem because it had the right sized, internal, condensing unit we wanted (27L/min. I think the equivalent Rinnai was 32L/min so quite a bit more expensive).

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#1646683 6-Oct-2016 14:50

The new bosch units that came out just last month called optiflow, can be controlled from your mobile phone via Bluetooth. Price was almost same as all the other brand 26l units. You can monitor gas usage i presume like power in powershop app. Saves paying extra for and installation of controller/s.

jonathan18

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#1646685 6-Oct-2016 14:55

Geese: The new bosch units that came out just last month called optiflow, can be controlled from your mobile phone via Bluetooth. Price was almost same as all the other brand 26l units. You can monitor gas usage i presume like power in powershop app. Saves paying extra for and installation of controller/s.

Interesting! Also, a much more stylish unit, I reckon: http://www.bosch-climate.co.nz/products-bosch-hot-water/hot-water-systems/domestic/boschoptiflow/boschoptiflow-26l.html

Probably too late for me now, given I've said yes to the Rinnai. Plus, good chance the price may not be as good if that's not the usual brand our plumber buys/installs.

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