Replacing Boilermate II with a MegaFlo

[SidDIYer]

Hi Everyone,

I have a Gledhill Boilermate II thermal store that is about 13 years old now and an Ideal Classic boiler. At some point, I would like to replace the Boilermate with a Megaflo. I'd like to know how much effort will be involved in the replacement. I understand that the boiler would probably have to change too but what I'd like to know is whether most of the work would be limited to the areas around the tank and the boiler i.e. the main pipes are in fact re-usable.

My Boilermate (if I've understood what I've looked at correctly) has a cold feed, an overflow to outside, a central heating output/return and of course a hot water output (all 22mm). Apart from new valves, pumps etc will there be a need to rip up floor boards between the Boilermate and the boiler?

I don't want to start a discussion about the relative merits of thermal stores (vented) vs Megaflos (unvented) vs combis. I have read quite a bit about all three in the last few months and believe that a Megaflo would best suit my needs.

Many thanks.

 

[mickyg]

its usually a relatively straight forward swap. Don't get a megaflo though, waste of money. Just as good UV cylinders out there cheaper and without the stupid bubble top,

 

[GaytonTonner]

Hi Everyone,

I have a Gledhill Boilermate II thermal store that is about 13 years old now and an Ideal Classic boiler. At some point, I would like to replace the Boilermate with a Megaflo. I'd like to know how much effort will be involved in the replacement. I understand that the boiler would probably have to change too but what I'd like to know is whether most of the work would be limited to the areas around the tank and the boiler i.e. the main pipes are in fact re-usable.

My Boilermate (if I've understood what I've looked at correctly) has a cold feed, an overflow to outside, a central heating output/return and of course a hot water output (all 22mm). Apart from new valves, pumps etc will there be a need to rip up floor boards between the Boilermate and the boiler?

I don't want to start a discussion about the relative merits of thermal stores (vented) vs Megaflos (unvented) vs combis. I have read quite a bit about all three in the last few months and believe that a Megaflo would best suit my needs.

Many thanks.

You have to pay for an annual service on the Megflow. The Boilermate also acts as buffer for the CH. The boiler lasts longer on a thermal store because of the near elimination of boiler cycling. These important points are not appreciated by the average jobbing plumber, who regard a thermal store as equivalent to an unvented cylinder. They are not. A cheaper simpler, boiler can be used which runs in optimal conditions. Replacement of pressure valves on an unvented are expensive.

Your system is piped for a thermal store. Replace with a stainless steel Advance Appliances unit, which is a simple swap. The cold feed does not get blocked on these and being stainless will last and last. The Boilermate only gets blocked in the cold feed (not a major event) in very hard water areas if neglected. Also with your Boilermate. put about 3 cans of X-100 in it.
http://advanceappliances.co.uk/gas_or_oil_thermal_store_systems.html

Put a Smart pump on the CH circuit and you can have TRVs all around. No auto by-passes or the likes.

BTW, Boilermates are not problematic. They suffer from ignorance. Look at the ignorance about simple combis installations...
//www.diynot.com/forums/viewtopic.php?t=257089

 

[Hugh Jaleak]

The OP said:

I don't want to start a discussion about the relative merits of thermal stores (vented) vs Megaflos (unvented) vs combis.

Which part of that dont you understand GT?

 

[GaytonTonner]

The OP said:

I don't want to start a discussion about the relative merits of thermal stores (vented) vs Megaflos (unvented) vs combis.

Which part of that dont you understand GT?

He thinks he has figured it out, going on ignorance on this forum. He hasn't and on the wrong track.

 

[simond]

Crikey, you wonder why you aren't taken seriously GT? It is ironic that the tradesmen you find such derision for haven't had to change their usernames at least 4 times on this forum.

A heatstore has a place in this World, and I have installed a few over the years where circumstances dictated, but it isn't the automatic answer every time someone mentions a desire for an unvented cylinder.

I think Mickyg is spot on, a Megaflo is probably the worst choice of unvented, the patented floating baffle just floats, no more. It doesn't stop the water depleting the air gap. If you read the Megaflo literature with this fact in mind you will see that they only say their baffle helps.

In a normal unvented the water is separated from the air by an impermeable membrane in an external vessel, which stops the problem.

The Megaflo is the only unvented I know of where they have stick a large label on the jacket advising the homeowner that leakage is to be expected after a few years. It is a triumph of product marketing over technical ability.

 

[SidDIYer]

The OP said:

I don't want to start a discussion about the relative merits of thermal stores (vented) vs Megaflos (unvented) vs combis.

Which part of that dont you understand GT?

He thinks he has figured it out, going on ignorance on this forum. He hasn't and on the wrong track.

Hi GT,

Since you ask a Combi is not suitable for me because of the amount of work that would be required to pipe it in. My boiler is in the kitchen and the Boilermate is in the 1st floor airing cupboard. As I understand, the hot water feed would have to be routed to the kitchen if I installed a Combi. If I wanted to move the boiler, say to the loft, then the gas will have to be moved as well as all the other pipes. I don't mind sacrificing the airing cupboard to a cylinder.

I understand that the Boilermate acts as a CH buffer and promotes boiler longevity by reducing cycling, but surely that's an argument against Combis too then? Also, thermal stores can't use condensing boilers ( last but one paragraph - http://www.miketheboilerman.com/Thermalstores.htm )

Thanks for the link to Advance Appliances. I noticed that they also do unvented cylinders too for which they offer a 25 year warranty vs only a 5 year warranty for the thermal store. Why the discrepancy?

As for unvented cylinder explosions, I have seen the MythBusters videos and it seems that you need to go to quite some lengths in order to get them to rupture. Regular maintenance will ensure that this won't happen. Boilers and Boilermates need regular maintenace too. Many of the comments on this board state that the known problems with Boilermates are due to home-owners not looking after them i.e. not having them serviced regularly. I lived with an unvented cylinder in an all-electric flat and was quite happy with it (Telford Tempest).

The chap that re-commissioned the Boilermate for me poured in 3 litres of "Center Central Heating Inhibitor" made by Wolseley UK. Is that the same as X100?

Many thanks.

 

[simond]

Yes, any inhibitor is better than none.

I think Mike the Boilerman has an excellent site but there is no way that condensing boilers won't condense with a thermal store, that is simply incorrect.

 

[mysteryman]

They will only condense on a thermal store if the store is stratified. If not, the whole store has to be way above condensing temperature to get any hot water. Better to connect the rads straight to a system boiler with weather comp.

However, that wasn't what the OP asked about!

 

[muggles]

The OP said:

I don't want to start a discussion about the relative merits of thermal stores (vented) vs Megaflos (unvented) vs combis.

Which part of that dont you understand GT?

He thinks he has figured it out, going on ignorance on this forum. He hasn't and on the wrong track.

Hi GT,

Since you ask a Combi is not suitable for me because of the amount of work that would be required to pipe it in. My boiler is in the kitchen and the Boilermate is in the 1st floor airing cupboard. As I understand, the hot water feed would have to be routed to the kitchen if I installed a Combi. If I wanted to move the boiler, say to the loft, then the gas will have to be moved as well as all the other pipes. I don't mind sacrificing the airing cupboard to a cylinder.

I understand that the Boilermate acts as a CH buffer and promotes boiler longevity by reducing cycling, but surely that's an argument against Combis too then? Also, thermal stores can't use condensing boilers ( last but one paragraph - http://www.miketheboilerman.com/Thermalstores.htm )

Thanks for the link to Advance Appliances. I noticed that they also do unvented cylinders too for which they offer a 25 year warranty vs only a 5 year warranty for the thermal store. Why the discrepancy?

As for unvented cylinder explosions, I have seen the MythBusters videos and it seems that you need to go to quite some lengths in order to get them to rupture. Regular maintenance will ensure that this won't happen. Boilers and Boilermates need regular maintenace too. Many of the comments on this board state that the known problems with Boilermates are due to home-owners not looking after them i.e. not having them serviced regularly. I lived with an unvented cylinder in an all-electric flat and was quite happy with it (Telford Tempest).

The chap that re-commissioned the Boilermate for me poured in 3 litres of "Center Central Heating Inhibitor" made by Wolseley UK. Is that the same as X100?

Many thanks.

Ah, it seems that you have GT sussed. Ignore him, his favourite phrase is "high flow combi", he seems to think it's the answer to pretty much everything. Also he isn't an installer, he's just a troll who lingers around here, presumably because he has little else to do. With a bit of luck he'll be banned again soon

Look at OSO Super S hot water cylinders, IMHO they're the best. And you're quite right, a correctly-installed and maintained UV cylinder won't explode. The risk is really very very tiny indeed.

Center CH Inhibitor is rebadged Fernox F1, which is a good quality inhibitor

 

[GaytonTonner]

They will only condense on a thermal store if the store is stratified. If not, the whole store has to be way above condensing temperature to get any hot water.

This is totally wrong. Condensing boilers condense in over 80% of reheat time when set to 80C. 90% plus when set lower. Most thermal stores can be set lower. The return temperature is the key and thermal stores get quite cool at the bottom.

Better to connect the rads straight to a system boiler with weather comp.

Using a thermal store means more condensing and reduced need for weather compensation. And using a cheapish simple boiler.

 

[GaytonTonner]

Yes, any inhibitor is better than none.

I think Mike the Boilerman has an excellent site but there is no way that condensing boilers won't condense with a thermal store, that is simply incorrect.

Yep. Spot on.

 

[SidDIYer]

Hi All,

Firstly, apologies. I didn't mean for this thread to degenerate into a flame war regarding the merits (or not) of unvented cylinders but it looks like it did.

Hi GT,

Thanks for all your comments to date. It seems that you have a number of concerns and issues with unvented cylinders. Of course, you're perfectly entitled to your own opinion.

He thinks he has figured it out, going on ignorance on this forum. He hasn't and on the wrong track.

GT, there's nothing that you've added to this thread that I didn't already know. I will still replace the Boilermate with an unvented cylinder when the BM finally conks out. I would prefer an unvented cylinder to all the other choices out there and that's my opinion.

All the best.

 

[GaytonTonner]

Hi GT,

Thanks for all your comments to date. It seems that you have a number of concerns and issues with unvented cylinders. Of course, you're perfectly entitled to your own opinion.

Is is not an opinion. It is engineering analysis backed by over 30 years of experience.

You already have a thermal store, which you have no complaints about in performance, the system is designed around that. You can replace type for type and even improve on what you have. Cheaply!

Do not go by narrow experienced jobbing plumbers. You read them here, "I only fit Vaillant and unvented cylinders and nothing", etc.

If you are insistent on fitting an unvented cylinder, against all logic, buy an direct version. Then have a combi heat it from the fresh water section. Use a brass pump, Wilo do a well priced one, and put it on the return from the cylinder (the cold feed to the combi), with a check valve after the pump.

When the cylinder stat calls for heat, the brass pumps cut in. The combi fires and heats the cylinder. The smallest DHW rated combi will do. The unvented cylinder may be smaller as the recovery rate is very fast. The combi puts the hot DHW at the top of the cylinder ready for draw off. Have decent flow combi, 13 litres or so, and use a Surrey flange at the unvented cylinder draw-off, and you will never run out of DHW. When the cylinder is depleted it reverts to what the combi can output. The brass pump creates suction in the cylinder with the water at the bottom running into the combi.

This is common practice on the Continent. It is cheap because a cheaper, smaller direct cylinder is used. I have done this with all electric houses with in place unvented cylinders when converting to a gas CH/DHW system. It is like having a storage combi, but using separate parts. An electric immersion can be fitted.

The combi will last as it only fires for continuous burns to re-heat the cylinder fast. It will not constantly switch on for short draw-off tap-turn ons, as normal combis do.

 

[SidDIYer]

Hi GT,

Thanks for all your comments to date. It seems that you have a number of concerns and issues with unvented cylinders. Of course, you're perfectly entitled to your own opinion.

Is is not an opinion. It is engineering analysis backed by over 30 years of experience.

You already have a thermal store, which you have no complaints about in performance, the system is designed around that. You can replace type for type and even improve on what you have. Cheaply!

Do not go by narrow experienced jobbing plumbers. You read them here, "I only fit Vaillant and unvented cylinders and nothing", etc.

If you are insistent on fitting an unvented cylinder, against all logic, buy an direct version. Then have a combi heat it from the fresh water section. Use a brass pump, Wilo do a well priced one, and put it on the return from the cylinder (the cold feed to the combi), with a check valve after the pump.

When the cylinder stat calls for heat, the brass pumps cut in. The combi fires and heats the cylinder. The smallest DHW rated combi will do. The unvented cylinder may be smaller as the recovery rate is very fast. The combi puts the hot DHW at the top of the cylinder ready for draw off. Have decent flow combi, 13 litres or so, and use a Surrey flange at the unvented cylinder draw-off, and you will never run out of DHW. When the cylinder is depleted it reverts to what the combi can output. The brass pump creates suction in the cylinder with the water at the bottom running into the combi.

This is common practice on the Continent. It is cheap because a cheaper, smaller direct cylinder is used. I have done this with all electric houses with in place unvented cylinders when converting to a gas CH/DHW system. It is like having a storage combi, but using separate parts. An electric immersion can be fitted.

The combi will last as it only fires for continuous burns to re-heat the cylinder fast. It will not constantly switch on for short draw-off tap-turn ons, as normal combis do.

I definitely can't install a combi because of the amount of building work that would be required to plumb it in. The option you describe does sound interesting though - has anyone else seen/done something similar?