Glowworm Fuelsaver F

[Christian McArdle]

Does anyone know if the Glowworm Fuelsaver F is suitable for running on a pressurised system? Although it will be retired in a couple of weeks, I'd like to lash it up to my hot water cylinder, as it lets me (a) get on with the pipework for the new boiler and (b) save a fortune in electricity.

It won't actually be run on a pressurised system, but the venting won't really be suitable for use with a boiler without a high temperature manual reset interlock. (it will take a convoluted route involving plastic pipework to the header tank standing on stilts above the HWC).

There's no obvious reset button (at least with the case on), so I'm not holding out much hope. It does have electronic ignition, however.

Christian.

[IMM]

If it is the copper tube heat exchanger then yes.

Even if it is not suitable, running it at a reduced pressure 0.5 will proibably do no harm for 3 weeks or so. I recall in the 1970s on London, when few sealed systems were around, many cast iron boilers in flats that were not suitable, running as pressure systems as it elimninated the bulky F&E tanks. Few had problems.

[Christian McArdle]

How would I tell which heat exchanger was fitted?

Christian.

[Christian McArdle]

Also, as a temporary hookup, is it possible to pump the flow from the boiler before the vent/feed?

i.e. __ / \ / | | | |----| < f&e tank | +--+-+

+------+ PUMP A | | |BOILER|--->>>-----+-----------+----+--+ +------+ | | | Z Z | | | | radiators HWC | | B | +---------------+-------------------+

Obviously this is assuming the boiler really does have the required cutouts.

The issue is that pipes A & B are long plastic pipes going into the loft. I can't have an additional pipe. There would be no path from the tank feed into the system to quench the boiler if it boils. The boiler steam would travel along plastic pipe A, probably melting it.

There probably only be a manual feed via a filling loop into the pipework to replenish water. The overflow would be a bucket. The "pressure gauge" would be looking into the tank.

Eventually, the old boiler and pump will be removed. The new boiler will be at the HWC end of the circuit, complete with the pressure relief valve and expansion vessel, meaning the f&e tank can go. As the pressure relief valve and expansion vessel are built into the boiler, I don't want to buy discrete versions.

Christian.

P.S. I've just remembered something I've done already that probably means I should have a high temp cutout anyway...

[IMM]

Have a look. You will see copper tubes with copper fins. I'm sure they only made one type of heat exchanger for the Fuelsaver.

[Christian McArdle]

Where is the reset button on them? Do I need to take the case off? I've always assumed it was an open flue because it had a viewing window for the flame.

Is it room sealed or open? I don't really want to remove the case off it unless it is open flued.

Christian.

[Ed Sirett]

If the new HW cylinder is properly insulated and your HW demands are normal then I doubt the electricty consumption will be very high for a few weeks.

[IMM]

As a temporary measure that is fine. The open vent tee must be "after" the cold feed tee, and both tees must be right next to each other, in order to prevent pumping over.

The Fuelsaver does have a high limit stat (mandatory for sealed systems) as well as a run stat. If it was open vented then the high limit was redundant, but useful as a fallback.

Boiler makers say plastic is fine, so the same could happen if a normal open vented system over boiled.

As long as you keep monitoring it, it should be fine as a temp measure.

[IMM]

If I recall correctly there isn't one.

If it is open flued you will have a conventional flue.

[Christian McArdle]

Well, it was really the first issue that was more compelling for me. I'd like to get all the pipework finished before the boiler goes in, which should make it a nice and easy job for John, without all that pesky lifting floorboards malarkey. It's just unfortunate that the new cylinder is above the level of the current F&E tank.

Christian.

[Christian McArdle]

So what happens when the high limit stat goes? Is it some trick like turning the thermostat to zero and then back up again?

I've got the impression that the 'F' in Fuelsaver F might be for fanned. I had a quick look at the flue last night and it appears that it might well be fanned. It is rectangular and really quite small. I suspect there are air and exhaust channels alongside each other.

Christian.

[IMM]

It just cuts off, and then when it cools it comes back in, just lke any other stat. Yiu will know there is a problem as the rads will be far too hot.

The Fuelsaver used to have a switch, that switched from high temp to low temp. No variable stat. It just switched from one pre-set stat to another, with a high limit to protect all. The high limit was at the side of the heat exchanger. Later models may have had a re-set button on the high limit stat which was not user accessible.

You will hear a fan. There was natural a convection balanced flue version and conventional flue versions using a normal open flue pipe.

[Christian McArdle]

I thought it had to be manual reset. In any case, if it has two stats, I'm less worried about it if it is only for a few weeks. I might try to remember to turn the system off when I'm not in the house.

Christian.

[IMM]

The early versions certainly did not. I think later models did have a re-set on the high limit stat.

It had three. A low temp, high temp and high limit. If say the high temp stat went then switch to the low temp to get around it.

Good idea.