New central heating system - opinion needed on components

teiching · 3 Oct 2007

Hi all,

We are currently about to replace our central heating system. The current setup is a Potterton Suprima 50 conventional boiler witha Gledhill Boilermate III (190 litres) vented thermal storage tank. The system is supposed to heat water for 3 bathrooms and quite a few radiators in a 3 bedroom detached house. The main problem was that the Boilermate failed to provide DHW. So we got the heat exchanger and one pump exchanged. Additionally the boiler sometimes stopped working probably due to overheating and not being designed to work with the Boilermate. We already had plumbers around a couple of times who occasionally could fix the problem, but there is still no guarantee that it will work for ever. So we decided to get a new system in.

Option 1:
Glowworm Flexicom 18hx High Efficiency Boiler + Albion Mainsflow Indirect Contractor 30/210 TS 1730x450mm

Option 2:
Vaillant Eco-Tec plus 428 open vented condensing boiler + Haetrae Sadia Megaflo HE 210 unvented hot water cylinder

We heard quite a few good things about Vaillant and Magaflo, but Option 2 would be the most expensive one and require some more pipework to be done in the house.

Option 1 is cheaper, but we don't have a clue about the reliability of the components, so we would appreciate if anyone could give some feedback on this

Also once someone gave us a quote for a combiboiler instead of boiler + tank. But turned out that this is completly out of question and probably wouldn't help us at all. Also would have caused the most disruption in the house.

Thanks in advance,

Tom

gas4you · 3 Oct 2007

Option 2 is no doubt the best, but drop the Megaflo and put in a Vaillant Unistor and connect both with a VR65 control unit.

Foregt thermal stores they cost too much to run.

And before the incompetent drivel on here says anything, modern unvented cylinders DO NOT need an annual service, just the safety devices checked.

teiching · 4 Oct 2007

Thanks gas4you. Haven't thought about that option yet. Sounds feasible to me. Do you know anyone in SW London who is specialized on Vaillant installs and whome you can recommend?

Any comments on the Glowwarm Flexicom Boiler and the Albion cylinder. Would be interested to get some opinion about these. Thanks

Agile · 5 Oct 2007

Where has Dr Drivel gone?

He will tell you your existing store is the best option in the whole planet!

Tony

Balenza · 5 Oct 2007

teiching wrote

Haetrae Sadia Megaflo HE 210 unvented hot water cylinder

Id be wary about an unvented cylinder in my home. They can do this if not installed or maintained properly.

http://www.waterheaterblast.com/

What made the water heater explode in the video?

We used a new, 12 gallon water heater (typically, water heaters in homes are at about 4 times this size)
For heating, we used a standard, 4500 watt heating element.
We began with 0 (zero) pounds of pressure. Typical homes have between 40 and 80 pounds of pressure.
As water heats, it expands which results in a pressure increase. In our demonstration, it took about 1 1/2 hours to rise from 0 to 410 psi which is the pressure at which the tank exploded.
The water temperature was about 400 degrees. When the tank ruptured, the water erupted into a steam explosion.
These are the same conditions that could exist if your thermostat became stuck "on" and your T&P was faulty.

John M · 5 Oct 2007

Couple of questions here ........ What did need servicing ?

Why they so steenking expensive ? ....... Gonna make my own outta copper & lotsa jubilee clips

Sing along now: "Fly me to the moon, up among the stars" ...... "Shoobie doo"........ "Jupiter & mars"

gas4you · 5 Oct 2007

teiching said:
Thanks gas4you. Haven't thought about that option yet. Sounds feasible to me. Do you know anyone in SW London who is specialized on Vaillant installs and whome you can recommend?

Any comments on the Glowwarm Flexicom Boiler and the Albion cylinder. Would be interested to get some opinion about these. Thanks

Don't know anything about the Albion cylinder so can't fairly comment.

Steer clear of the Glow Worm though, inferior boilers made for the cheaper end of the market and don't come with a full 2 year warranty.

Balenza · 5 Oct 2007

Page 4 in the link below shows what the side of your home could look like if one of these unvented beasts explode.

http://www.doli.state.mn.us/pdf/tenn_boiler_pictures.pdf

Yep, its a horrible great big hole and hopefully like the guy in the pic you will be on the outside looking in and still in one piece.

doitall · 5 Oct 2007

Balenza said:
Page 4 in the link below shows what the side of your home could look like if one of these unvented beasts explode.

http://www.doli.state.mn.us/pdf/tenn_boiler_pictures.pdf

Yep, its a horrible great big hole and hopefully like the guy in the pic you will be on the outside looking in and still in one piece.

You do talk some Ballski Ballenski.

An unvented cylinder has never ever exploded in the Country and is never ever likely too, unless some pratt blocks all the safety devices up.

The cylinder in the film you/drivel/salesman/water sytems love to entertain the boys with was doctored for effect on the American market.

In reality you would have to be the unluckiest man on the planet if it exploded.

Pressure relief valve.
Temperature pressure relief valve.
Thermal cut-out.
Spring close MV.
Cylinder expansion.
Boiler stat.
Boiler pressure relief valve.
Over heatcut-out.
Faulty stat.
Boiler expansion vessel.

Everyone of the above would have to fail before it came close to exploding

Agile · 5 Oct 2007

I dont think you looked at that link John!

Its a large STEAM boiler! Perhaps about 300 kW !

Tony

Balenza · 5 Oct 2007

And this is what the boiler inspectors concluded in their report.

Based on the foregoing, it is concluded that the main cause of the boiler accident was improper maintenance and the lack of operational procedures of the boilers. In addition, removal and replacement of critical controls and safety devices, along with the lack of proper training and qualified personnel equally contributed to the occurrence of the accident.

As may happen one day with a UV cylinder in the UK.

Balenza · 5 Oct 2007

Doitall wrote

Everyone of the above would have to fail before it came close to exploding

Err no, you could have an immersion bossed direct unit and one fails and mebbe the prv's are concreted shut due to scale, debris or lack of maintance and then KABOOOOOOOOOOOOOOOOOOOOOOOOOOOM.

Gasguru · 5 Oct 2007

Sorry Balenza but your saying the heater thermostat would have to fail ON, the overheat stat would have to fail ON, the TP valve would fail SHUT and the E valve would fail SHUT. 1 in a 100000000000000 chance I reckon.

AFAIK there has never been a reported incident with unvented cylinders (on land) exploding in the UK. You would need to bypass several safety devices to cause an explosion. Even the most incompetent cowboy is unlikely to cause a problem.

The only incident I can recall was a "home made" effort on board a fishing vessel. The cylinder utilised was a standard grade 3 copper cylinder. No safety devices were fitted and despite obvious problems with the installation (steam from taps) the captain still had no concerns. When it finally blew a hole through his vessel he reconsidered.

More chance of getting hit on the head by blue ice than an UV cylinder exploding.

bripl · 5 Oct 2007

as much as i like thermal stores installed correctly this one is worth avoiding
Albion Mainsflow Indirect Contractor 30/210 TS 1730x450mm

it may have reliabilty probs.

doitall · 5 Oct 2007

Apart from the overheat stat on the immersion heater, theres still the thermal cut-out to fail as well.

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New central heating system - opinion needed on components

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