Combi boiler heating systems

My builder is installing a combi boiler hot water/ heating system in a holiday flat that we are planning to let out. He does not appear to be fitting a room thermostat or any sort of timer. Is this normal for such a system?

I can understand not having a room thermostat as all radiators (except one) have TRVs but the lack of a timer concerns me. I don't want enormous bills because the heating is on 24 hours a day.

Can anyone please advise me on what is normal?

Thanks

Jonathan

Reply to
Jonathan
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It's not ideal but it should work i guess.

All the radiators should be able to have TRV's as Combi systems normally have an internal bypass circuit. You will be able to adjust the desired flow temperature. So provided this isn't too high, the boiler will just modulate or switch off when the flow temperature is reached.

Doesn't sound ideal to have the pump running 24x7 though....

Reply to
chunkyoldcortina

There are some combis that can be supplied with an internal time clock/programmer - for instance Ideal Isar.

Reply to
Jim

The combi could have a timer included in it. For example:-

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Reply to
chudford

You need a "control interlock", by law. That means a way of cutting out the boiler when no heat is needed in the house. This is normally done by having a room stat with no TRV on the rad. Having the boiler open up a by-pass and cycle on itself is very inefficient and can lead to premature boiler failure.

The stat can be a timer/stat, so timing solved. A combi cannot have TRVs all around, unless there is an integral flow switch. Some Baxi models have this feature, like the HE 133.

One way around not having an integral flow switch is install an auto modulating Smart pump on the return pipe to the combi and flow switch just after that. Wire the combis stat circuit through the flow switch. This means you have two pumps in push me pull you configuration. If the combis integral pump is on the return put the smart pump on the flow.

When the TRVs all close up the flow switch switches out the combi's pump and burner and the Smart pump winds down. When the TRVs open up the Smart pump winds up and switches in the flow switch which switches in the combi burner and pump. No central stat then and TRVs all around. You use two pumps, so it may be a good idea to put in a restrictor balancing valve on the CH return to restrict the flow of the two pumps. Then the Smart pump will wind down and not use a large amount of electrical energy.

Reply to
Doctor Drivel

Looks like a good deal with the 3 year guarantee. I wonder why the insurance company I use (Domestic&General) wants a hefty premium to cover it for breakdown. Maybe they just load it according to the initial price of the boiler. Anyone got any opinions about them?

Reply to
Stuart Noble

The company load it for only the Ravenheat? Ravenheat are generally a waste of sheet metal. I believe one or two of the simple heating boilers are OK. They also rebadge one I think, and this is OK too.

In one job they had reservations on a high flow combi because they wanted DHW backup. To go for a cylinder or heat bank would have meant taking up valuable space and more expense. A cheap backup option was a quality main high flow combi and a cheapo B&Q £300 combi as backup. The backup was fitted below the main combi (sizable under the stairs cupboard). To install the cylinder and a new immersion cable and the rest would have been far, far more expensive that the cheapo backup combi. The CU breaker, switch and immersion and cable would have been more than the cheap combi.

They had full DHW & CH backup (OK DHW was reduced flowrate) and the same gas supply was used for both as they would not be on at the same time - a throw over switch was use to prevent both being on. The cheapo combi would be used once in a blue moon, so no reliability problems. The pipework and effort in installing the extra combi was negligible.

So cheapo combis have their uses.

Reply to
Doctor Drivel

Excellent idea. Cheap combis are known for their reliability - far better than an immersion heater. And of course everyone has room for one along with the main one. Remind us of the planet you're from?

Reply to
Dave Plowman (News)

No, and it won't meet current building regs...

A better solution is to dispense with the timer and use a programmable room stat. This allows selection of desired temperature through several time periods in the day. Hence it does the job of stat, programmer, and frost stat all in one. A basic one is about £20.

Reply to
John Rumm

Please eff off as you a complete and total idiotic plantpot.

Reply to
Doctor Drivel

Planet woodentop, then. Are they all barking mad?

Reply to
Dave Plowman (News)

Please eff off as you a complete and total idiotic plantpot.

Reply to
Doctor Drivel

Check the back of his CORGI card (Gas Safe card from 1 Apr) it should say whether it has 'Energy Efficiency'. If it has then they should know and act better. Timer, thermostat and TRVs are all needed. If it doesn't they they shouldn't be installing a heating system.

Reply to
Ed Sirett

That's not correct for the combis I'm familiar with.

Reply to
YAPH

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