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There is a common misconception about caravan hot water systems that I've seen inferred to by several posters elsewhere recently. Caravan water heating is not an 'instant hot water system'. By that I mean the water is not drawn straight from a cold source and heated as it moves to the tap. In fact it's a stored hot water system, a mini immersion heater type, if you will.

The boiler has a storage tank, or water jacket around the heat source, or sources and this water jacket firstly has to be filled when you first put cold water into the van, either from an Aquaroll, a direct mains feed or an onboard cold water tank. The boiler has a water capacity of between 5 and 10 litres (depending on the brand/model) and as the boiler is the first port of call for incoming fresh water, it has to fill up first before any water then proceeds to fill up the pipes to the taps. This is why it always seems to take a long time for water to initially reach the taps.

Before providing power/gas to heat the boiler you should always ensure that you're getting a steady, non-spluttering stream of cold water at the hot tap. That indicates that the boiler is full and ready to be heated.

Generally it takes about 30 minutes for the boiler full of cold water to become hot water. This can be shortened a bit by running gas and electric water heating together if your boiler has that option. Once the water is hot it will be kept that way by the boiler thermostat which will switch on an element, or gas as it senses the temperature reducing. Once hot, you can turn off the boiler power supply and it will stay hot for quite a while.

Obviously when hot water is used at sink, basin or shower, it will be replaced in the boiler by more cold water which will reduce the tank water temperature and, if switched on, the boiler thermostat will get the heating to kick in again. If you use up all the hot water in the boiler, on, say, a shower, then it will take around 30 minutes to warm the boiler contents again.

From all of this it follows that if you've got a full flow when the shower mixer is turned to hot, then there's no supply problem and the boiler is full. If you've had warm water through the mixer in the past then it's being fed by the boiler and the boiler was working. If the boiler has been turned on for any good length of time and the water is still cold, then there's a problem with the boiler/energy supply. If you're getting spluttering then it's likely that the system hasn't filled properly yet. Pulsing on and off is a weird one and the first check would be to locate and listen to the pump to hear if it is pulsing too, or if it's an issue somewhere in the internal van piping. One possibility is that the water level in the source is such that the pump is pulling in air as well as water and is having difficulty building sufficient head of water. In that case fill the source or move the pump so it's fully submerged. Another possibility is that there's a leak somewhere that's letting air into the pipework and the pump can't build a head of water, though where air leaks in, water tends to leak out and that tends to be visible.

Some systems have a pump regulator device which sets at which pressure the pump will switch off/on, this is often heard clicking off. if it's set wrong it may cause 'hunting' of the pump. Without seeing and/or knowing the system involved it's hard to be more precise.    

I've got nothing to do on this hot afternoon

but to settle down and write you a line.

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Posted (edited)

Check if there is a thermostatic valve on the water supply to the shower, I seem to remember seeing one on a photo, possibly might have been one from Griff. If there is one it might need adjusting. Pulsing flow is not right though.

Edited by Paul1957
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 Was it this one this one Paul?

 

 

Stay safe - Griff.  :ph34r:

Wheels at the front Green Oval Towing Machine

Wheels at the back Bessacarr 845

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32 minutes ago, Griff said:

 Was it this one this one Paul?

 

 

That is the one I was thinking about.

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Do Coachman use such valves?

I've got nothing to do on this hot afternoon

but to settle down and write you a line.

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Posted (edited)

I would strongly recommend getting the road wheels balanced at the earliest opportunity (unless Coachman has already done it).  Caravan wheels, especially alloy rims, are notorious for being out of balance and can require upwards of 50g of weights to correct the inbalance.  It's good for the running gear, the caravan body and its contents.

I would also strongly recommend a TPMS like TyrePal.

Edited by Crannoghome
added TPMS
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21 hours ago, Griff said:

 Was it this one this one Paul?

Sadly I can't see one of those anywhere as that would have been a good suggestion.

On 25/04/2021 at 17:42, 8ftWanderer said:The water seems to run a bit start / stop. In other words the water freely flows then seems to take a quite break and then flow again.

Good news! I have cured the pulsating water supply issue.

 

I fixed it by re-calibrating the IC Control unit on the inside of the van where the Whale Pump plugs in. After doing the calibration the water now flows continuously. Happy days!

 

Bad news!

 

However, the hot water flow to the shower is still a problem. It is just a trickle and has no pressure. Incidentally the hot taps bathroom and kitchen are fine and when they are on the pump kicks in. However, when running the shower on hot only it just trickles and the pump doesn't run which to me would suggest the root of the lack of pressure.

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It might be worth trying to check the pipe-run to the shower as it is possible that one of them (or both) have been trapped/crushed while something else has been fitted.  Of course you shouldn't have to and it should have been picked up during the PDI inspection but if it is something simple it might be easier than dragging it back to the dealer.

2018 Volvo V90 and 2018 Swift Sprite Quattro EB

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Posted (edited)
54 minutes ago, 8ftWanderer said:

 

However, the hot water flow to the shower is still a problem. It is just a trickle and has no pressure. Incidentally the hot taps bathroom and kitchen are fine and when they are on the pump kicks in. However, when running the shower on hot only it just trickles and the pump doesn't run which to me would suggest the root of the lack of pressure.

As Gary has pointed out, this sounds like something is restricting the shower water flow. Since you are only getting a trickle flow, the water pressure is not dropping enough for the pump to run - try the shower and then also turn on another tap at the same time to see if the pump runs which will confirm this. Remove the shower head and also its hose and see if that helps in case it is blocked or has a filter in it that is blocked. Then as Gary suggests, check all the pipes/fittings to it. Maybe also check the mixer tap in case it is blocked - you could even remove it and try a hose pipe water supply through it or try swapping the hot and cold pipes over to it and if the cold flow then drops off you will know it is the mixer tap. The shower hose should be a large bore type to reduce pressure drop and help give more flow.

 

The IC control is just a fancy pressure switch which can compensate for varying battery voltages and not need adjusting once set. The pressure switches work by starting the pump when the water pressure falls as a tap is opened. When the tap is closed the pressure in the pipes rises and the switch turns the pump off. If not set right and the pressure is set too low, the pump will start/stop frequently when a tap is opened and give a pulsing flow and the pump can bang around in the aqua roll.

Edited by Paul1957
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Somebody posted elsewhere that they found a rubber washer in the back of their shower control unit which hadn't been fitted properly and was trapped, partially blocking the entry into the unit. As the basin is OK it has to be a problem between where the basin hot supply branches off and the shower.

I've got nothing to do on this hot afternoon

but to settle down and write you a line.

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1 hour ago, Steamdrivenandy said:

it has to be a problem between where the basin hot supply branches off and the shower.

Yes, I have eliminated the shower hose so it’s either at the back of the valve or some way along the branch pipe after the sink.

 

it would involve tools and undoing fixings and I don’t want to go there with it being brand new.

 

A trip to the dealers looks inevitable.

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A breakthrough!

 

I have man handled the shower valve and found it would turn a little whilst in situ. By jiggling it around and changing its position it has freed up the flow of the hot water.

 

Clearly it wasn’t fitted correctly and it will still need a visit to the dealers to refit it.

 

However, at least I have found the source of the issue and it prevents them lifting floors and undoing panelling in search of the problem.

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